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abstract. suppose an orientation preserving action of a finite group g on the closed surface σg of genus g > 1 extends over the 3-torus t 3 for some embedding σg ⊂ t 3 . then |g| ≤ 12(g − 1), and this upper bound 12(g − 1) can be achieved for g = n2 + 1, 3n2 + 1, 2n3 + 1, 4n3 + 1, 8n3 + 1, n ∈ z+ . those surfaces in t 3 realizing the maximum symmetries can be either unknotted or knotted. similar problems in non-orientable category is also discussed. connection with minimal surfaces in t 3 is addressed and when the maximum symmetric surfaces above can be realized by minimal surfaces is identified.
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abstract. hypergroups are lifted to power semigroups with negation, yielding a method of transferring results from semigroup theory. this applies to analogous structures such as hypergroups, hyperfields, and hypermodules, and permits us to transfer the general theory espoused in [19] to the hypertheory.
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abstract—general video game playing (gvgp) aims at designing an agent that is capable of playing multiple video games with no human intervention. in 2014, the general video game ai (gvgai) competition framework was created and released with the purpose of providing researchers a common open-source and easy to use platform for testing their ai methods with potentially infinity of games created using video game description language (vgdl). the framework has been expanded into several tracks during the last few years to meet the demand of different research directions. the agents are required to either play multiples unknown games with or without access to game simulations, or to design new game levels or rules. this survey paper presents the vgdl, the gvgai framework, existing tracks, and reviews the wide use of gvgai framework in research, education and competitions five years after its birth. a future plan of framework improvements is also described.
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abstract diagnosis for tccp using a linear temporal logic marco comini, laura titolo dimi, università degli studi di udine, italy (e-mail: [email protected])
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abstract we prove that every non-trivial valuation on an infinite superrosy field of positive characteristic has divisible value group and algebraically closed residue field. in fact, we prove the following more general result. let k be a field such that for every finite extension l of k and for every natural number n > 0 the index [l∗ : (l∗ )n ] is finite and, if char(k) = p > 0 and f : l → l is given by f (x) = xp − x, the index [l+ : f [l]] is also finite. then either there is a non-trivial definable valuation on k, or every non-trivial valuation on k has divisible value group and, if char(k) > 0, it has algebraically closed residue field. in the zero characteristic case, we get some partial results of this kind. we also notice that minimal fields have the property that every non-trivial valuation has divisible value group and algebraically closed residue field.
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abstract medium voltage direct-current based integrated power system is projected as one of the solutions for powering the all-electric ship. it faces significant challenges for accurately energizing advanced loads, especially the pulsed power load, which can be rail gun, high power radar, and other state of art equipment. energy storage based on supercapacitors is proposed as a technique for buffering the direct impact of pulsed power load on the power systems. however, the high magnitude of charging current of the energy storage can pose as a disturbance to both distribution and generation systems. this paper presents a fast switching device based real time control system that can achieve a desired balance between maintaining the required power quality and fast charging the energy storage in required time. test results are shown to verify the performance of the proposed control algorithm. keywords: medium voltage direct-current based integrated power system, pulsed power load, power quality, disturbance metric, real time control 1. introduction research related to navy shipboard power system raise a critical concern regarding to the system stability due to diverse loads. similar to microgrids, navy shipboard power systems do not have a slack bus [1]. it can be viewed as a microgrid always operating in islanding mode. compared with typical terrestrial microgrid, the ratio between the overall load and generation is much higher [2]. although new avenues such as zonal load architecture [3], high preprint submitted to international journal of electrical power and energy systemsjanuary 18, 2018
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abstract. let v be a symplectic vector space of dimension 2n. given a partition λ with at most n parts, there is an associated irreducible representation s[λ] (v ) of sp(v ). this representation admits a resolution by a natural complex lλ• , which we call the littlewood complex, whose terms are restrictions of representations of gl(v ). when λ has more than n parts, the representation s[λ] (v ) is not defined, but the littlewood complex lλ• still makes sense. the purpose of this paper is to compute its homology. we find that either lλ• is acyclic or it has a unique non-zero homology group, which forms an irreducible representation of sp(v ). the non-zero homology group, if it exists, can be computed by a rule reminiscent of that occurring in the borel–weil–bott theorem. this result can be interpreted as the computation of the “derived specialization” of irreducible representations of sp(∞), and as such categorifies earlier results of koike–terada on universal character rings. we prove analogous results for orthogonal and general linear groups. along the way, we will see two topics from commutative algebra: the minimal free resolutions of determinantal ideals and koszul homology.
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abstract we model individual t2dm patient blood glucose level (bgl) by stochastic process with discrete number of states mainly but not solely governed by medication regimen (e.g. insulin injections). bgl states change otherwise according to various physiological triggers which render a stochastic, statistically unknown, yet assumed to be quasi-stationary, nature of the process. in order to express incentive for being in desired healthy bgl we heuristically define a reward function which returns positive values for desirable bg levels and negative values for undesirable bg levels. the state space consists of sufficient number of states in order to allow for memoryless assumption. this, in turn, allows to formulate markov decision process (mdp), with an objective to maximize the total reward, summarized over a long run. the probability law is found by model-based reinforcement learning (rl) and the optimal insulin treatment policy is retrieved from mdp solution.
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abstract smoothness conditions and propose an orthonormal series estimator which attains the optimal rate of convergence. the performance of the estimator depends on the correct specification of a dimension parameter whose optimal choice relies on smoothness characteristics of both the intensity and the error density. since a priori knowledge of such characteristics is a too strong assumption, we propose a data-driven choice of the dimension parameter based on model selection and show that the adaptive estimator either attains the minimax optimal rate or is suboptimal only by a logarithmic factor.
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abstract
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abstract we consider the problem of estimating a low-rank signal matrix from noisy measurements under the assumption that the distribution of the data matrix belongs to an exponential family. in this setting, we derive generalized stein’s unbiased risk estimation (sure) formulas that hold for any spectral estimators which shrink or threshold the singular values of the data matrix. this leads to new data-driven spectral estimators, whose optimality is discussed using tools from random matrix theory and through numerical experiments. under the spiked population model and in the asymptotic setting where the dimensions of the data matrix are let going to infinity, some theoretical properties of our approach are compared to recent results on asymptotically optimal shrinking rules for gaussian noise. it also leads to new procedures for singular values shrinkage in finite-dimensional matrix denoising for gamma-distributed and poisson-distributed measurements.
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abstract. the k-restricted edge-connectivity of a graph g, denoted by λk (g), is defined as the minimum size of an edge set whose removal leaves exactly two connected components each containing at least k vertices. this graph invariant, which can be seen as a generalization of a minimum edge-cut, has been extensively studied from a combinatorial point of view. however, very little is known about the complexity of computing λk (g). very recently, in the parameterized complexity community the notion of good edge separation of a graph has been defined, which happens to be essentially the same as the k-restricted edge-connectivity. motivated by the relevance of this invariant from both combinatorial and algorithmic points of view, in this article we initiate a systematic study of its computational complexity, with special emphasis on its parameterized complexity for several choices of the parameters. we provide a number of np-hardness and w[1]-hardness results, as well as fpt-algorithms. keywords: graph cut; k-restricted edge-connectivity; good edge separation; parameterized complexity; fpt-algorithm; polynomial kernel.
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abstract mobile visual search applications are emerging that enable users to sense their surroundings with smart phones. however, because of the particular challenges of mobile visual search, achieving a high recognition bitrate has becomes a consistent target of previous related works. in this paper, we propose a few-parameter, low-latency, and high-accuracy deep hashing approach for constructing binary hash codes for mobile visual search. first, we exploit the architecture of the mobilenet model, which significantly decreases the latency of deep feature extraction by reducing the number of model parameters while maintaining accuracy. second, we add a hash-like layer into mobilenet to train the model on labeled mobile visual data. evaluations show that the proposed system can exceed state-of-the-art accuracy performance in terms of the map. more importantly, the memory consumption is much less than that of other deep learning models. the proposed method requires only 13 mb of memory for the neural network and achieves a map of 97.80% on the mobile location recognition dataset used for testing. index terms— mobile visual search, supervised hashing, binary code, deep learning 1. introduction with the proliferation of mobile devices, it is becoming possible to use mobile perception functionalities (e.g., cameras, gps, and wi-fi) to perceive the surrounding environment [1]. among such techniques, mobile visual search plays a key role in mobile localization, mobile media search, and mobile social networking. however, rather than simply porting traditional visual search methods to mobile platforms, for mobile visual search, one must face the challenges of a large auralvisual variance of queries, stringent memory and computation constraints, network bandwidth limitations, and the desire for an instantaneous search experience. this work was partially supported by the ccf-tencent open research fund (no. agr20160113), the national natural science foundation of china (no. 61632008), and the fundamental research funds for the central universities (no. 2016rcgd32).
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abstract we review boltzmann machines extended for time-series. these models often have recurrent structure, and back propagration through time (bptt) is used to learn their parameters. the perstep computational complexity of bptt in online learning, however, grows linearly with respect to the length of preceding time-series (i.e., learning rule is not local in time), which limits the applicability of bptt in online learning. we then review dynamic boltzmann machines (dybms), whose learning rule is local in time. dybm’s learning rule relates to spike-timing dependent plasticity (stdp), which has been postulated and experimentally confirmed for biological neural networks.
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abstract this paper presents two realizations of linear quantum systems for covariance assignment corresponding to pure gaussian states. the first one is called a cascade realization; given any covariance matrix corresponding to a pure gaussian state, we can construct a cascaded quantum system generating that state. the second one is called a locally dissipative realization; given a covariance matrix corresponding to a pure gaussian state, if it satisfies certain conditions, we can construct a linear quantum system that has only local interactions with its environment and achieves the assigned covariance matrix. both realizations are illustrated by examples from quantum optics. key words: linear quantum system, cascade realization, locally dissipative realization, covariance assignment, pure gaussian state.
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abstract this paper considers the synchronization problem for networks of coupled nonlinear dynamical systems under switching communication topologies. two types of nonlinear agent dynamics are considered. the first one is non-expansive dynamics (stable dynamics with a convex lyapunov function ϕ(·)) and the second one is dynamics that satisfies a global lipschitz condition. for the non-expansive case, we show that various forms of joint connectivity for communication graphs are sufficient for networks to achieve global asymptotic ϕ-synchronization. we also show that ϕ-synchronization leads to state synchronization provided that certain additional conditions are satisfied. for the globally lipschitz case, unlike the non-expansive case, joint connectivity alone is not sufficient for achieving synchronization. a sufficient condition for reaching global exponential synchronization is established in terms of the relationship between the global lipschitz constant and the network parameters. we also extend the results to leader-follower networks.
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abstracts franck dernoncourt∗ mit [email protected]
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abstract. the subject of this work is quantum predicative programming — the study of developing of programs intended for execution on a quantum computer. we look at programming in the context of formal methods of program development, or programming methodology. our work is based on probabilistic predicative programming, a recent generalisation of the well-established predicative programming. it supports the style of program development in which each programming step is proven correct as it is made. we inherit the advantages of the theory, such as its generality, simple treatment of recursive programs, time and space complexity, and communication. our theory of quantum programming provides tools to write both classical and quantum specifications, develop quantum programs that implement these specifications, and reason about their comparative time and space complexity all in the same framework.
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abstract we report on an extensive study of the current benefits and limitations of deep learning approaches to robot vision and introduce a novel dataset used for our investigation. to avoid the biases in currently available datasets, we consider a human-robot interaction setting to design a data-acquisition protocol for visual object recognition on the icub humanoid robot. considering the performance of off-the-shelf models trained on off-line large-scale image retrieval datasets, we show the necessity for knowledge transfer. indeed, we analyze different ways in which this last step can be done, and identify the major bottlenecks in robotics scenarios. by studying both object categorization and identification tasks, we highlight the key differences between object recognition in robotics and in image retrieval tasks, for which the considered deep learning approaches have been originally designed. in a nutshell, our results confirm also in the considered setting the remarkable improvements yield by deep learning, while pointing to specific open challenges that need to be addressed for seamless deployment in robotics.
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abstract—a source submits status updates to a network for delivery to a destination monitor. updates follow a route through a series of network nodes. each node is a last-come-first-served queue supporting preemption in service. we characterize the average age of information at the input and output of each node in the route induced by the updates passing through. for poisson arrivals to a line network of preemptive memoryless servers, we show that average age accumulates through successive network nodes.
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abstract—we use decision trees to build a helpdesk agent reference network to facilitate the on-the-job advising of junior or less experienced staff on how to better address telecommunication customer fault reports. such reports generate field measurements and remote measurements which, when coupled with location data and client attributes, and fused with organization-level statistics, can produce models of how support should be provided. beyond decision support, these models can help identify staff who can act as advisors, based on the quality, consistency and predictability of dealing with complex troubleshooting reports. advisor staff models are then used to guide less experienced staff in their decision making; thus, we advocate the deployment of a simple mechanism which exploits the availability of staff with a sound track record at the helpdesk to act as dormant tutors. index terms— customer relationship management; decision trees; knowledge flow graph
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abstract in multiagent systems, we often have a set of agents each of which have a preference ordering over a set of items and one would like to know these preference orderings for various tasks, for example, data analysis, preference aggregation, voting etc. however, we often have a large number of items which makes it impractical to ask the agents for their complete preference ordering. in such scenarios, we usually elicit these agents’ preferences by asking (a hopefully small number of) comparison queries — asking an agent to compare two items. prior works on preference elicitation focus on unrestricted domain and the domain of single peaked preferences and show that the preferences in single peaked domain can be elicited by much less number of queries compared to unrestricted domain. we extend this line of research and study preference elicitation for single peaked preferences on trees which is a strict superset of the domain of single peaked preferences. we show that the query complexity crucially depends on the number of leaves, the path cover number, and the distance from path of the underlying single peaked tree, whereas the other natural parameters like maximum degree, diameter, pathwidth do not play any direct role in determining query complexity. we then investigate the query complexity for finding a weak condorcet winner for preferences single peaked on a tree and show that this task has much less query complexity than preference elicitation. here again we observe that the number of leaves in the underlying single peaked tree and the path cover number of the tree influence the query complexity of the problem.
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abstract. scheduling theory is an old and well-established area in combinatorial optimization, whereas the much younger area of parameterized complexity has only recently gained the attention of the community. our aim is to bring these two areas closer together by studying the parameterized complexity of a class of single-machine two-agent scheduling problems. our analysis focuses on the case where the number of jobs belonging to the second agent is considerably smaller than the number of jobs belonging to the first agent, and thus can be considered as a fixed parameter k. we study a variety of combinations of scheduling criteria for the two agents, and for each such combination we pinpoint its parameterized complexity with respect to the parameter k. the scheduling criteria that we analyze include the total weighted completion time, the total weighted number of tardy jobs, and the total weighted number of just-in-time jobs. our analysis draws a borderline between tractable and intractable variants of these problems. ⋆
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abstract we study the capacitated k-median problem for which existing constant-factor approximation algorithms are all pseudo-approximations that violate either the capacities or the upper bound k on the number of open facilities. using the natural lp relaxation for the problem, one can only hope to get the violation factor down to 2. li [soda’16] introduced a novel lp to go beyond the limit of 2 and gave a constant-factor approximation algorithm that opens (1 + )k facilities. we use the configuration lp of li [soda’16] to give a constant-factor approximation for the capacitated k-median problem in a seemingly harder configuration: we violate only the capacities by 1 + . this result settles the problem as far as pseudo-approximation algorithms are concerned.
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abstract. a locally compact groupoid is said to have the weak containment property if its full c ∗ -algebra coincide with its reduced one. although it is now known that this property is strictly weaker than amenability, we show that the two properties are the same under a mild exactness assumption. then we apply our result to get informations about the corresponding weak containment property for some semigroups.
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abstract: in linear regression with fixed design, we propose two procedures that aggregate a data-driven collection of supports. the collection is a subset of the 2p possible supports and both its cardinality and its elements can depend on the data. the procedures satisfy oracle inequalities with no assumption on the design matrix. then we use these procedures to aggregate the supports that appear on the regularization path of the lasso in order to construct an estimator that mimics the best lasso estimator. if the restricted eigenvalue condition on the design matrix is satisfied, then this estimator achieves optimal prediction bounds. finally, we discuss the computational cost of these procedures.
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abstract— the paper considers the problem of cooperative estimation for a linear uncertain plant observed by a network of communicating sensors. we take a novel approach by treating the filtering problem from the view point of local sensors while the network interconnections are accounted for via an uncertain signals modelling of estimation performance of other nodes. that is, the information communicated between the nodes is treated as the true plant information subject to perturbations, and each node is endowed with certain believes about these perturbations during the filter design. the proposed distributed filter achieves a suboptimal h∞ consensus performance. furthermore, local performance of each estimator is also assessed given additional constraints on the performance of the other nodes. these conditions are shown to be useful in tuning the desired estimation performance of the sensor network.
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abstracting from these details, the fft and ifft take up a significant amount of compute resources, which we address in section 5. table 5: cufft convolution performance breakdown (k40m, ms) layer l1 fprop bprop accgrad l2 fprop bprop accgrad l3 fprop bprop accgrad l4 fprop bprop accgrad l5 fprop bprop accgrad
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abstraction for networks of control systems: a dissipativity approach
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abstract. completely random measures (crms) and their normalizations are a rich source of bayesian nonparametric priors. examples include the beta, gamma, and dirichlet processes. in this paper we detail two major classes of sequential crm representations—series representations and superposition representations—within which we organize both novel and existing sequential representations that can be used for simulation and posterior inference. these two classes and their constituent representations subsume existing ones that have previously been developed in an ad hoc manner for specific processes. since a complete infinite-dimensional crm cannot be used explicitly for computation, sequential representations are often truncated for tractability. we provide truncation error analyses for each type of sequential representation, as well as their normalized versions, thereby generalizing and improving upon existing truncation error bounds in the literature. we analyze the computational complexity of the sequential representations, which in conjunction with our error bounds allows us to directly compare representations and discuss their relative efficiency. we include numerous applications of our theoretical results to commonly-used (normalized) crms, demonstrating that our results enable a straightforward representation and analysis of crms that has not previously been available in a bayesian nonparametric context.
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abstract. this note presents a discussion of the algebraic and combinatorial aspects of the theory of pure o-sequences. various instances where pure o-sequences appear are described. several open problems that deserve further investigation are also presented.
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abstract by taking a variety of realistic hardware imperfections into consideration, we propose an optimal power allocation (opa) strategy to maximize the instantaneous secrecy rate of a cooperative wireless network comprised of a source, a destination and an untrusted amplify-and-forward (af) relay. we assume that either the source or the destination is equipped with a large-scale multiple antennas (lsma) system, while the rest are equipped with a single antenna. to prevent the untrusted relay from intercepting the source message, the destination sends an intended jamming noise to the relay, which is referred to as destination-based cooperative jamming (dbcj). given this system model, novel closedform expressions are presented in the high signal-to-noise ratio (snr) regime for the ergodic secrecy rate (esr) and the secrecy outage probability (sop). we further improve the secrecy performance of the system by optimizing the associated hardware design. the results reveal that by beneficially distributing the tolerable hardware imperfections across the transmission and reception radio-frequency (rf) front ends of each node, the system’s secrecy rate may be improved. the engineering insight is that equally sharing the total imperfections at the relay between the transmitter and the receiver provides the best secrecy performance. numerical results illustrate that the proposed opa together with the most appropriate hardware design significantly increases the secrecy rate.
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abstract feature learning with deep models has achieved impressive results for both data representation and classification for various vision tasks. deep feature learning, however, typically requires a large amount of training data, which may not be feasible for some application domains. transfer learning can be one of the approaches to alleviate this problem by transferring data from data-rich source domain to data-scarce target domain. existing transfer learning methods typically perform one-shot transfer learning and often ignore the specific properties that the transferred data must satisfy. to address these issues, we introduce a constrained deep transfer feature learning method to perform simultaneous transfer learning and feature learning by performing transfer learning in a progressively improving feature space iteratively in order to better narrow the gap between the target domain and the source domain for effective transfer of the data from source domain to target domain. furthermore, we propose to exploit the target domain knowledge and incorporate such prior knowledge as constraint during transfer learning to ensure that the transferred data satisfies certain properties of the target domain. to demonstrate the effectiveness of the proposed constrained deep transfer feature learning method, we apply it to thermal feature learning for eye detection by transferring from the visible domain. we also applied the proposed method for cross-view facial expression recognition as a second application. the experimental results demonstrate the effectiveness of the proposed method for both applications.
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abstract—we consider a finite-horizon linear-quadratic optimal control problem where only a limited number of control messages are allowed for sending from the controller to the actuator. to restrict the number of control actions computed and transmitted by the controller, we employ a threshold-based event-triggering mechanism that decides whether or not a control message needs to be calculated and delivered. due to the nature of threshold-based event-triggering algorithms, finding the optimal control sequence requires minimizing a quadratic cost function over a non-convex domain. in this paper, we firstly provide an exact solution to the non-convex problem mentioned above by solving an exponential number of quadratic programs. to reduce computational complexity, we, then, propose two efficient heuristic algorithms based on greedy search and the alternating direction method of multipliers (admm) method. later, we consider a receding horizon control strategy for linear systems controlled by event-triggered controllers, and we also provide a complete stability analysis of receding horizon control that uses finite horizon optimization in the proposed class. numerical examples testify to the viability of the presented design technique. index terms — optimal control; linear systems; eventtriggered control; receding horizon control
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abstract advancement in technology has generated abundant high-dimensional data that allows integration of multiple relevant studies. due to their huge computational advantage, variable screening methods based on marginal correlation have become promising alternatives to the popular regularization methods for variable selection. however, all these screening methods are limited to single study so far. in this paper, we consider a general framework for variable screening with multiple related studies, and further propose a novel two-step screening procedure using a self-normalized estimator for highdimensional regression analysis in this framework. compared to the one-step procedure and rank-based sure independence screening (sis) procedure, our procedure greatly reduces false negative errors while keeping a low false positive rate. theoretically, we show that our procedure possesses the sure screening property with weaker assumptions on signal strengths and allows the number of features to grow at an exponential rate of the sample size. in addition, we relax the commonly used normality assumption and allow sub-gaussian distributions. simulations and a real transcriptomic application illustrate the advantage of our method as compared to the rank-based sis method. key words and phrases: multiple studies, partial faithfulness, self-normalized estimator, sure screening property, variable selection
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abstract in the paper, a parallel tabu search algorithm for the resource constrained project scheduling problem is proposed. to deal with this np-hard combinatorial problem many optimizations have been performed. for example, a resource evaluation algorithm is selected by a heuristic and an effective tabu list was designed. in addition to that, a capacity-indexed resource evaluation algorithm was proposed and the gpu (graphics processing unit) version uses a homogeneous model to reduce the required communication bandwidth. according to the experiments, the gpu version outperforms the optimized parallel cpu version with respect to the computational time and the quality of solutions. in comparison with other existing heuristics, the proposed solution often gives better quality solutions. cite as: libor bukata, premysl sucha, zdenek hanzalek, solving the resource constrained project scheduling problem using the parallel tabu search designed for the cuda platform, journal of parallel and distributed computing, volume 77, march 2015, pages 58-68, issn 0743-7315, http://dx.doi. org/10.1016/j.jpdc.2014.11.005. source code: https://github.com/ctu-iig/rcpspcpu, https://github.com/ctu-iig/rcpspgpu keywords: resource constrained project scheduling problem, parallel tabu search, cuda, homogeneous model, gpu 1. introduction the resource constrained project scheduling problem (rcpsp), which has a wide range of applications in logistics, manufacturing and project management [1], is a universal and well-known problem in the operations research domain. the problem can be briefly described using a set of ∗
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abstract—this paper is concerned with optimization of distributed broadband wireless communication (bwc) systems. bwc systems contain a distributed antenna system (das) connected to a base station with optical fiber. distributed bwc systems have been proposed as a solution to the power constraint problem in traditional cellular networks. so far, the research on bwc systems have advanced on two separate tracks, design of the system to meet the quality of service requirements (qos) and optimization of location of the das. in this paper, we consider a combined optimization of bwc systems. we consider uplink communications in distributed bwc systems with multiple levels of priority traffic with arrivals and departures forming renewal processes. we develop an analysis that determines packet delay violation probability for each priority level as a function of the outage probability of the das through the application of results from renewal theory. then, we determine the optimal locations of the antennas that minimize the antenna outage probability. we also study the trade off between the packet delay violation probability and packet loss probability. this work will be helpful in the designing of the distributed bwc systems. index terms— queuing delay, multiple levels of priority traffic, distributed antenna system (das), outage probability, antenna placement.
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abstract like classical block codes, a locally repairable code also obeys the singleton-type bound (we call a locally repairable code optimal if it achieves the singleton-type bound). in the breakthrough work of [14], several classes of optimal locally repairable codes were constructed via subcodes of reed-solomon codes. thus, the lengths of the codes given in [14] are upper bounded by the code alphabet size q. recently, it was proved through extension of construction in [14] that length of q-ary optimal locally repairable codes can be q + 1 in [7]. surprisingly, [2] presented a few examples of q-ary optimal locally repairable codes of small distance and locality with code length achieving roughly q 2 . very recently, it was further shown in [8] that there exist q-ary optimal locally repairable codes with length bigger than q + 1 and distance propositional to n. thus, it becomes an interesting and challenging problem to construct new families of q-ary optimal locally repairable codes of length bigger than q + 1. in this paper, we construct a class of optimal locally repairable codes of distance 3 and 4 with unbounded length (i.e., length of the codes is independent of the code alphabet size). our technique is through cyclic codes with particular generator and parity-check polynomials that are carefully chosen.
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abstract  let b = b (x) , x ∈ s2 be the fractional brownian motion indexed by the unit sphere s2 with index 0 < h ≤ 21 , introduced by istas [12]. we establish optimal upper and lower bounds for its angular power spectrum {dℓ , ℓ = 0, 1, 2, . . .}, and then exploit its high-frequency behavior to establish the property of its strong local nondeterminism of b.
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abstract)∗ davide corona†
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abstract we give effective proofs of residual finiteness and conjugacy separability for finitely generated nilpotent groups. in particular, we give precise asymptotic bounds for a function introduced by bou-rabee that measures how large the quotients that are needed to separate non-identity elements of bounded length from the identity which improves the work of bou-rabee. similarly, we give polynomial upper and lower bounds for an analogous function introduced by lawton, louder, and mcreynolds that measures how large the quotients that are needed to separate pairs of distinct conjugacy classes of bounded word length using work of blackburn and mal’tsev.
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abstract—in a device-to-device (d2d) underlaid massive mimo system, d2d transmitters reuse the uplink spectrum of cellular users (cus), leading to cochannel interference. to decrease pilot overhead, we assume pilot reuse (pr) among d2d pairs. we first derive the minimum-mean-square-error (mmse) estimation of all channels and give a lower bound on the ergodic achievable rate of both cellular and d2d links. to mitigate pilot contamination caused by pr, we then propose a pilot scheduling and pilot power control algorithm based on the criterion of minimizing the sum mean-square-error (mse) of channel estimation of d2d links. we show that, with an appropriate pr ratio and a well designed pilot scheduling scheme, each d2d transmitter could transmit its pilot with maximum power. in addition, we also maximize the sum rate of all d2d links while guaranteeing the quality of service (qos) of cus, and develop an iterative algorithm to obtain a suboptimal solution. simulation results show that the effect of pilot contamination can be greatly decreased by the proposed pilot scheduling algorithm, and the pr scheme provides significant performance gains over the conventional orthogonal training scheme in terms of system spectral efficiency.
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abstract nitsche’s method is a popular approach to implement dirichlet-type boundary conditions in situations where a strong imposition is either inconvenient or simply not feasible. the method is widely applied in the context of unfitted finite element methods. from the classical (symmetric) nitsche’s method it is well-known that the stabilization parameter in the method has to be chosen sufficiently large to obtain unique solvability of discrete systems. in this short note we discuss an often used strategy to set the stabilization parameter and describe a possible problem that can arise from this. we show that in specific situations error bounds can deteriorate and give examples of computations where nitsche’s method yields large and even diverging discretization errors. keywords: nitsche’s method, unfitted/immersed finite element methods, penalty/stabilization parameter, accuracy, stability, error analysis
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abstract we investigate the performance of the finite volume method in solving viscoplastic flows. the creeping square lid-driven cavity flow of a bingham plastic is chosen as the test case and the constitutive equation is regularised as proposed by papanastasiou [j. rheology 31 (1987) 385-404]. it is shown that the convergence rate of the standard simple pressure-correction algorithm, which is used to solve the algebraic equation system that is produced by the finite volume discretisation, severely deteriorates as the bingham number increases, with a corresponding increase in the non-linearity of the equations. it is shown that using the simple algorithm in a multigrid context dramatically improves convergence, although the multigrid convergence rates are much worse than for newtonian flows. the numerical results obtained for bingham numbers as high as 1000 compare favorably with reported results of other methods. keywords: bingham plastic, papanastasiou regularisation, lid-driven cavity, finite volume method, simple, multigrid this is the accepted version of the article published in: journal of non-newtonian fluid mechanics 195 (2013) 19–31, doi:10.1016/j.jnnfm.2012.12.008 c 2016. this manuscript version is made available under the cc-by-nc-nd 4.0 license http: //creativecommons.org/licenses/by-nc-nd/4.0/ 1. introduction viscoplastic flows constitute an important branch of non-newtonian fluid mechanics, as many materials of industrial, geophysical, and biological importance are known to exhibit yield stress. in general, yield-stress fluids are suspensions of particles or macromolecules, such as pastes, gels, foams, drilling fluids, food products, and nanocomposites. a comprehensive review of viscoplasticity has been carried out by barnes [1]. such materials behave as (elastic or inelastic) solids, below a certain critical shear stress level, i.e. the yield stress, and as liquids otherwise. the flow field is thus divided into unyielded (rigid) and yielded (fluid) regions. ∗
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abstract for computer vision applications, prior works have shown the efficacy of reducing numeric precision of model parameters (network weights) in deep neural networks. activation maps, however, occupy a large memory footprint during both the training and inference step when using mini-batches of inputs. one way to reduce this large memory footprint is to reduce the precision of activations. however, past works have shown that reducing the precision of activations hurts model accuracy. we study schemes to train networks from scratch using reduced-precision activations without hurting accuracy. we reduce the precision of activation maps (along with model parameters) and increase the number of filter maps in a layer, and find that this scheme matches or surpasses the accuracy of the baseline full-precision network. as a result, one can significantly improve the execution efficiency (e.g. reduce dynamic memory footprint, memory bandwidth and computational energy) and speed up the training and inference process with appropriate hardware support. we call our scheme wrpn - wide reduced-precision networks. we report results and show that wrpn scheme is better than previously reported accuracies on ilsvrc-12 dataset while being computationally less expensive compared to previously reported reduced-precision networks.
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abstract. let g be an abelian group and s be a g-graded a noetherian algebra over a commutative ring a ⊆ s0 . let i1 , . . . , is be g-homogeneous ideals in s, and let m be a finitely generated g-graded s-module. we show that the shape of nonzero g-graded betti numbers of m i1t1 . . . ists exhibit an eventual linear behavior as the ti s get large.
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abstract. it is well-known that the factorization properties of a domain are reflected in the structure of its group of divisibility. the main theme of this paper is to introduce a topological/graph-theoretic point of view to the current understanding of factorization in integral domains. we also show that connectedness properties in the graph and topological space give rise to a generalization of atomicity.
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abstract the large-system performance of maximum-a-posterior estimation is studied considering a general distortion function when the observation vector is received through a linear system with additive white gaussian noise. the analysis considers the system matrix to be chosen from the large class of rotationally invariant random matrices. we take a statistical mechanical approach by introducing a spin glass corresponding to the estimator, and employing the replica method for the large-system analysis. in contrast to earlier replica based studies, our analysis evaluates the general replica ansatz of the corresponding spin glass and determines the asymptotic distortion of the estimator for any structure of the replica correlation matrix. consequently, the replica symmetric as well as the replica symmetry breaking ansatz with b steps of breaking is deduced from the given general replica ansatz. the generality of our distortion function lets us derive a more general form of the maximum-a-posterior decoupling principle. based on the general replica ansatz, we show that for any structure of the replica correlation matrix, the vector-valued system decouples into a bank of equivalent decoupled linear systems followed by maximum-a-posterior estimators. the structure of the decoupled linear system is further studied under both the replica symmetry and the replica symmetry breaking assumptions. for b steps of symmetry breaking, the decoupled system is found to be an additive system with a noise term given as the sum of an independent gaussian random variable with b correlated impairment terms. the general decoupling property of the maximum-a-posterior estimator leads to the idea of a replica simulator which represents the replica ansatz through the state evolution of a transition system described by its corresponding decoupled system. as an application of our study, we investigate large compressive sensing systems by considering the ℓp norm minimization recovery schemes. our numerical investigations show that the replica symmetric ansatz for ℓ0 norm recovery fails to give an accurate approximation of the mean square error as the compression rate grows, and therefore, the replica symmetry breaking ansätze are needed in order to assess the performance precisely. index terms maximum-a-posterior estimation, linear vector channel, decoupling principle, equivalent single-user system, compressive sensing, zero norm, replica method, statistical physics, replica symmetry breaking, replica simulator the results of this manuscript were presented in parts at 2016 ieee information theory workshop (itw) [78] and 2017 ieee information theory and applications workshop (ita) [79]. this work was supported by the german research foundation, deutsche forschungsgemeinschaft (dfg), under grant no. mu 3735/2-1. ali bereyhi and ralf r. müller are with the institute for digital communications (idc), friedrich alexander university of erlangen-nürnberg (fau), konrad-zuse-straße 5, 91052, erlangen, bavaria, germany (e-mails: [email protected], [email protected]). hermann schulz-baldes is with the department of mathematics, fau, cauerstraße 11, 91058, erlangen, bavaria, germany (e-mail: schuba@ mi.uni-erlangen.de).
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abstract hi, robby, can you get my cup from the cupboard?
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abstract. we prove that the autonomous norm on the group of compactly supported hamiltonian diffeomorphisms of the standard r2n is bounded.
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abstract to help mitigate road congestion caused by the unrelenting growth of traffic demand, many transit authorities have implemented managed lane policies. managed lanes typically run parallel to a freeway’s standard, general-purpose (gp) lanes, but are restricted to certain types of vehicles. it was originally thought that managed lanes would improve the use of existing infrastructure through incentivization of demand-management behaviors like carpooling, but implementations have often been characterized by unpredicted phenomena that is often to detrimental system performance. development of traffic models that can capture these sorts of behaviors is a key step for helping managed lanes deliver on their promised gains. towards this goal, this paper presents several macroscopic traffic modeling tools we have used for study of freeways equipped with managed lanes, or “managed lane-freeway networks.” the proposed framework is based on the widely-used first-order kinematic wave theory. in this model, the gp and the managed lanes are modeled as parallel links connected by nodes, where certain type of traffic may switch between gp and managed lane links. two types of managed lane configuration are considered: full-access, where vehicles can switch between the gp and the managed lanes anywhere; and separated, where such switching is allowed only at certain locations called gates. we incorporate two phenomena into our model that are particular to managed lane-freeway networks: the inertia effect and the friction effect. the inertia effect reflects drivers’ inclination to stay in their lane as long as possible and switch only if this would obviously improve their travel condition. the friction effect reflects the empirically-observed driver fear of moving fast in a managed lane while traffic in the adjacent gp links moves slowly due to congestion. calibration of models of large road networks is difficult, as the dynamics depend on many parameters whose numbers grow with the network’s size. we present an iterative learning-based approach to calibrating our model’s physical and driver-behavioral parameters. finally, we validate our model and calibration methodology with case studies of simulations of two managed lane-equipped california freeways.
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abstract compiler working with abstract functions modelled directly in the theorem prover’s logic is defined and proven sound. then, this compiler is refined to a concrete version that returns a target-language expression.
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abstract—this paper proposes xml-defined network policies (xdnp), a new high-level language based on xml notation, to describe network control rules in software defined network environments. we rely on existing openflow controllers specifically floodlight but the novelty of this project is to separate complicated language- and framework-specific apis from policy descriptions. this separation makes it possible to extend the current work as a northbound higher level abstraction that can support a wide range of controllers who are based on different programming languages. by this approach, we believe that network administrators can develop and deploy network control policies easier and faster. index terms—software defined networks; openflow; floodlight; sdn compiler; sdn programming languages; sdn abstraction.
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abstract in this paper we present linear time approximation schemes for several generalized matching problems on nonbipartite graphs. our results include o (m)-time algorithms for (1 − )maximum weight f -factor and (1 + )-approximate minimum weight f -edge cover. as a byproduct, we p also obtain direct algorithms for the exact cardinality versions of these problems running in o(m f (v )) time. the technical contributions of this work include an efficient method for maintaining relaxed complementary slackness in generalized matching problems and approximation-preserving reductions between the f -factor and f -edge cover problems.
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abstract. we call an ideal in a polynomial ring robust if it can be minimally generated by a universal gröbner basis. in this paper we show that robust toric ideals generated by quadrics are essentially determinantal. we then discuss two possible generalizations to higher degree, providing a tight classification for determinantal ideals, and a counterexample to a natural extension for lawrence ideals. we close with a discussion of robustness of higher betti numbers.
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abstract the major challenges of automatic track counting are distinguishing tracks and material defects, identifying small tracks and defects of similar size, and detecting overlapping tracks. here we address the latter issue using wusem, an algorithm which combines the watershed transform, morphological erosions and labeling to separate regions in photomicrographs. wusem shows reliable results when used in photomicrographs presenting almost isotropic objects. we tested this method in two datasets of diallyl phthalate (dap) photomicrographs and compared the results when counting manually and using the classic watershed. the mean automatic/manual efficiency ratio when using wusem in the test datasets is 0.97 ± 0.11. keywords: automatic counting, diallyl phthalate, digital image processing, fission track dating
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abstract—this paper considers the massive connectivity application in which a large number of potential devices communicate with a base-station (bs) in a sporadic fashion. the detection of device activity pattern together with the estimation of the channel are central problems in such a scenario. due to the large number of potential devices in the network, the devices need to be assigned non-orthogonal signature sequences. the main objective of this paper is to show that by using random signature sequences and by exploiting sparsity in the user activity pattern, the joint user detection and channel estimation problem can be formulated as a compressed sensing single measurement vector (smv) problem or multiple measurement vector (mmv) problem, depending on whether the bs has a single antenna or multiple antennas, and be efficiently solved using an approximate message passing (amp) algorithm. this paper proposes an amp algorithm design that exploits the statistics of the wireless channel and provides an analytical characterization of the probabilities of false alarm and missed detection by using the state evolution. we consider two cases depending on whether the large-scale component of the channel fading is known at the bs and design the minimum mean squared error (mmse) denoiser for amp according to the channel statistics. simulation results demonstrate the substantial advantage of exploiting the statistical channel information in amp design; however, knowing the large-scale fading component does not offer tangible benefits. for the multiple-antenna case, we employ two different amp algorithms, namely the amp with vector denoiser and the parallel amp-mmv, and quantify the benefit of deploying multiple antennas at the bs. index terms—device activity detection, channel estimation, approximate message passing, compressed sensing, internet of things (iot), machine-type communications (mtc)
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abstract. we give a new, simple distributed algorithm for graph colouring in paths and cycles. our algorithm is fast and self-contained, it does not need any globally consistent orientation, and it reduces the number of colours from 10100 to 3 in three iterations.
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abstract. this paper provides an induction rule that can be used to prove properties of data structures whose types are inductive, i.e., are carriers of initial algebras of functors. our results are semantic in nature and are inspired by hermida and jacobs’ elegant algebraic formulation of induction for polynomial data types. our contribution is to derive, under slightly different assumptions, a sound induction rule that is generic over all inductive types, polynomial or not. our induction rule is generic over the kinds of properties to be proved as well: like hermida and jacobs, we work in a general fibrational setting and so can accommodate very general notions of properties on inductive types rather than just those of a particular syntactic form. we establish the soundness of our generic induction rule by reducing induction to iteration. we then show how our generic induction rule can be instantiated to give induction rules for the data types of rose trees, finite hereditary sets, and hyperfunctions. the first of these lies outside the scope of hermida and jacobs’ work because it is not polynomial, and as far as we are aware, no induction rules have been known to exist for the second and third in a general fibrational framework. our instantiation for hyperfunctions underscores the value of working in the general fibrational setting since this data type cannot be interpreted as a set.
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abstract. step-indexed semantic interpretations of types were proposed as an alternative to purely syntactic proofs of type safety using subject reduction. the types are interpreted as sets of values indexed by the number of computation steps for which these values are guaranteed to behave like proper elements of the type. building on work by ahmed, appel and others, we introduce a step-indexed semantics for the imperative object calculus of abadi and cardelli. providing a semantic account of this calculus using more ‘traditional’, domain-theoretic approaches has proved challenging due to the combination of dynamically allocated objects, higher-order store, and an expressive type system. here we show that, using step-indexing, one can interpret a rich type discipline with object types, subtyping, recursive and bounded quantified types in the presence of state.
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abstract it was shown recently that the k l1-norm principal components (l1-pcs) of a real-valued data matrix x ∈ rd×n (n data samples of d dimensions) can be exactly calculated with cost o(2n k ) or, when advantageous, o(n dk−k+1 ) where d = rank(x), k < d [1], [2]. in applications where x is large (e.g., “big” data of large n and/or “heavy” data of large d), these costs are prohibitive. in this work, we present a novel suboptimal algorithm for the calculation of the k < d l1-pcs of x of cost o(n dmin{n, d} + n 2 (k 4 + dk 2 ) + dn k 3 ), which is comparable to that of standard (l2-norm) pc analysis. our theoretical and experimental studies show that the proposed algorithm calculates the exact optimal l1-pcs with high frequency and achieves higher value in the l1-pc optimization metric than any known alternative algorithm of comparable computational cost. the superiority of the calculated l1-pcs over standard l2-pcs (singular vectors) in characterizing potentially faulty data/measurements is demonstrated with experiments on data dimensionality reduction and disease diagnosis from genomic data.
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abstract—we present a structural clustering algorithm for large-scale datasets of small labeled graphs, utilizing a frequent subgraph sampling strategy. a set of representatives provides an intuitive description of each cluster, supports the clustering process, and helps to interpret the clustering results. the projection-based nature of the clustering approach allows us to bypass dimensionality and feature extraction problems that arise in the context of graph datasets reduced to pairwise distances or feature vectors. while achieving high quality and (human) interpretable clusterings, the runtime of the algorithm only grows linearly with the number of graphs. furthermore, the approach is easy to parallelize and therefore suitable for very large datasets. our extensive experimental evaluation on synthetic and real world datasets demonstrates the superiority of our approach over existing structural and subspace clustering algorithms, both, from a runtime and quality point of view.
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abstract as nuclear power expands, technical, economic, political, and environmental analyses of nuclear fuel cycles by simulators increase in importance. to date, however, current tools are often fleet-based rather than discrete and restrictively licensed rather than open source. each of these choices presents a challenge to modeling fidelity, generality, efficiency, robustness, and scientific transparency. the cyclus nuclear fuel cycle simulator framework and its modeling ecosystem incorporate modern insights from simulation science and software architecture to solve these problems so that challenges in nuclear fuel cycle analysis can be better addressed. a summary of the cyclus fuel cycle simulator framework and its modeling ecosystem are presented. additionally, the implementation of each is discussed in the context of motivating challenges in nuclear fuel cycle simulation. finally, the current capabilities of cyclus are demonstrated for both open and closed fuel cycles. keywords: nuclear fuel cycle, simulation, agent based modeling, nuclear engineering, object orientation, systems analysis
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abstract this paper describes autonomous racing of rc race cars based on mathematical optimization. using a dynamical model of the vehicle, control inputs are computed by receding horizon based controllers, where the objective is to maximize progress on the track subject to the requirement of staying on the track and avoiding opponents. two different control formulations are presented. the first controller employs a two-level structure, consisting of a path planner and a nonlinear model predictive controller (nmpc) for tracking. the second controller combines both tasks in one nonlinear optimization problem (nlp) following the ideas of contouring control. linear time varying models obtained by linearization are used to build local approximations of the control nlps in the form of convex quadratic programs (qps) at each sampling time. the resulting qps have a typical mpc structure and can be solved in the range of milliseconds by recent structure exploiting solvers, which is key to the real-time feasibility of the overall control scheme. obstacle avoidance is incorporated by means of a high-level corridor planner based on dynamic programming, which generates convex constraints for the controllers according to the current position of opponents and the track layout. the control performance is investigated experimentally using 1:43 scale rc race cars, driven at speeds of more than 3 m/s and in operating regions with saturated rear tire forces (drifting). the algorithms run at 50 hz sampling rate on embedded computing platforms, demonstrating the real-time feasibility and high performance of optimization-based approaches for autonomous racing.
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abstract: polarization-division multiplexed (pdm) transmission based on the nonlinear fourier transform (nft) is proposed for optical fiber communication. the nft algorithms are generalized from the scalar nonlinear schrödinger equation for one polarization to the manakov system for two polarizations. the transmission performance of the pdm nonlinear frequency-division multiplexing (nfdm) and pdm orthogonal frequency-division multiplexing (ofdm) are determined. it is shown that the transmission performance in terms of q-factor is approximately the same in pdm-nfdm and single polarization nfdm at twice the data rate and that the polarization-mode dispersion does not seriously degrade system performance. compared with pdm-ofdm, pdm-nfdm achieves a q-factor gain of 6.4 db. the theory can be generalized to multi-mode fibers in the strong coupling regime, paving the way for the application of the nft to address the nonlinear effects in space-division multiplexing. © 2017 optical society of america ocis codes: (060.2330) fiber optics communications,(060.4230) multiplexing, (060.4370) nonlinear optics, fibers
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abstract. in this paper we propose an algorithm for the numerical solution of arbitrary differential equations of fractional order. the algorithm is obtained by using the following decomposition of the differential equation into a system of differential equation of integer order connected with inverse forms of abel-integral equations. the algorithm is used for solution of the linear and non-linear equations.
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abstract. the klee’s measure of n axis-parallel boxes in rd is the volume of their union. it can be computed in time within o(nd/2 ) in the worst case. we describe three techniques to boost its computation: one based on some type of “degeneracy” of the input, and two ones on the inherent “easiness” of the structure of the input. the first technique benefits from instances where the maxima of the input is of small size h, and yields a solution running in time within o(n log2d−2 h + hd/2 ) ⊆ o(nd/2 ). the second technique takes advantage of instances where no d-dimensional axis-aligned hyperplane intersects more than k boxes in some dimension, and yields a solution running in time within o(n log n+nk(d−2)/2 ) ⊆ o(nd/2 ). the third technique takes advantage of instances where the intersection graph of the input has small treewidth ω. it yields an algorithm running in time within o(n4 ω log ω+n(ω log ω)d/2 ) in general, and in time within o(n log n + nω d/2 ) if an optimal tree decomposition of the intersection graph is given. we show how to combine these techniques in an algorithm which takes advantage of all three configurations.
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abstract—using a drone as an aerial base station (abs) to provide coverage to users on the ground is envisaged as a promising solution for beyond fifth generation (beyond-5g) wireless networks. while the literature to date has examined downlink cellular networks with abss, we consider an uplink cellular network with an abs. specifically, we analyze the use of an underlay abs to provide coverage for a temporary event, such as a sporting event or a concert in a stadium. using stochastic geometry, we derive the analytical expressions for the uplink coverage probability of the terrestrial base station (tbs) and the abs. the results are expressed in terms of (i) the laplace transforms of the interference power distribution at the tbs and the abs and (ii) the distance distribution between the abs and an independently and uniformly distributed (i.u.d.) abssupported user equipment and between the abs and an i.u.d. tbs-supported user equipment. the accuracy of the analytical results is verified by monte carlo simulations. our results show that varying the abs height leads to a trade-off between the uplink coverage probability of the tbs and the abs. in addition, assuming a quality of service of 90% at the tbs, an uplink coverage probability of the abs of over 85% can be achieved, with the abs deployed at or below its optimal height of typically between 250 − 500 m for the considered setup.
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abstract many evolutionary and constructive heuristic approaches have been introduced in order to solve the traveling thief problem (ttp). however, the accuracy of such approaches is unknown due to their inability to find global optima. in this paper, we propose three exact algorithms and a hybrid approach to the ttp. we compare these with state-of-theart approaches to gather a comprehensive overview on the accuracy of heuristic methods for solving small ttp instances.
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abstract the quest for algorithms that enable cognitive abilities is an important part of machine learning. a common trait in many recently investigated cognitive-like tasks is that they take into account different data modalities, such as visual and textual input. in this paper we propose a novel and generally applicable form of attention mechanism that learns high-order correlations between various data modalities. we show that high-order correlations effectively direct the appropriate attention to the relevant elements in the different data modalities that are required to solve the joint task. we demonstrate the effectiveness of our high-order attention mechanism on the task of visual question answering (vqa), where we achieve state-of-the-art performance on the standard vqa dataset.
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abstract very important breakthroughs in data-centric machine learning algorithms led to impressive performance in ‘transactional’ point applications such as detecting anger in speech, alerts from a face recognition system, or ekg interpretation. nontransactional applications, e.g. medical diagnosis beyond the ekg results, require ai algorithms that integrate deeper and broader knowledge in their problem-solving capabilities, e.g. integrating knowledge about anatomy and physiology of the heart with ekg results and additional patient’s findings. similarly, for military aerial interpretation, where knowledge about enemy doctrines on force composition and spread helps immensely in situation assessment beyond image recognition of individual objects. an initiative is proposed to build wikipedia for smart machines, meaning target readers are not human, but rather smart machines. named rekopedia, the goal is to develop methodologies, tools, and automatic algorithms to convert humanity knowledge that we all learn in schools, universities and during our professional life into reusable knowledge structures that smart machines can use in their inference algorithms. ideally, rekopedia would be an open source shared knowledge repository similar to the well-known shared open source software code repositories. the double deep learning approach advocates integrating data-centric machine self-learning techniques with machineteaching techniques to leverage the power of both and overcome their corresponding limitations. for illustration, an outline of a $15m project is described to produce reko knowledge modules for medical diagnosis of about 1,000 disorders. ai applications that are based solely on data-centric machine learning algorithms are typically point solutions for transactional tasks that do not lend themselves to automatic generalization beyond the scope of the data sets they are based on. today’s ai industry is fragmented, and we are not establishing broad and deep enough foundations that will enable us to build higher level ‘generic’, ‘universal’ intelligence, let alone ‘super-intelligence’. we must find ways to create synergies between these fragments and connect them with external knowledge sources, if we wish to scale faster the ai industry. examples in the article are based on- or inspired by- real-life non-transactional ai systems i deployed over decades of ai career that benefit hundreds of millions of people around the globe. we are now in the second ai ‘spring’ after a long ai ‘winter’. to avoid sliding again into an ai winter, it is essential that we rebalance the roles of data and knowledge. data is important but knowledge- deep and commonsense- are equally important.
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abstract we demonstrate that the integrality gap of the natural cut-based lp relaxation for the directed steiner tree problem is o(log k) in quasi-bipartite graphs with k terminals. such instances can be seen to generalize set cover, so the integrality gap analysis is tight up to a constant factor. a novel aspect of our approach is that we use the primal-dual method; a technique that is rarely used in designing approximation algorithms for network design problems in directed graphs.
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abstract recent approaches based on artificial neural networks (anns) have shown promising results for named-entity recognition (ner). in order to achieve high performances, anns need to be trained on a large labeled dataset. however, labels might be difficult to obtain for the dataset on which the user wants to perform ner: label scarcity is particularly pronounced for patient note de-identification, which is an instance of ner. in this work, we analyze to what extent transfer learning may address this issue. in particular, we demonstrate that transferring an ann model trained on a large labeled dataset to another dataset with a limited number of labels improves upon the state-of-the-art results on two different datasets for patient note de-identification.
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abstract: we discuss relations between residual networks (resnet), recurrent neural networks (rnns) and the primate visual cortex. we begin with the observation that a shallow rnn is exactly equivalent to a very deep resnet with weight sharing among the layers. a direct implementation of such a rnn, although having orders of magnitude fewer parameters, leads to a performance similar to the corresponding resnet. we propose 1) a generalization of both rnn and resnet architectures and 2) the conjecture that a class of moderately deep rnns is a biologically-plausible model of the ventral stream in visual cortex. we demonstrate the effectiveness of the architectures by testing them on the cifar-10 dataset.
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abstract. we study the ramification theory for actions involving group schemes, focusing on the tame ramification. we consider the notion of tame quotient stack introduced in [aov] and the one of tame action introduced in [cept]. we establish a local slice theorem for unramified actions and after proving some interesting lifting properties for linearly reductive group schemes, we establish a slice theorem for actions by commutative group schemes inducing tame quotient stacks. roughly speaking, we show that these actions are induced from an action of an extension of the inertia group on a finitely presented flat neighborhood. we finally consider the notion of tame action and determine how this notion is related to the one of tame quotient stack previously considered.
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abstract. we propose a new statistical procedure able in some way to overcome the curse of dimensionality without structural assumptions on the function to estimate. it relies on a least-squares type penalized criterion and a new collection of models built from hyperbolic biorthogonal wavelet bases. we study its properties in a unifying intensity estimation framework, where an oracle-type inequality and adaptation to mixed smoothness are shown to hold. besides, we describe an algorithm for implementing the estimator with a quite reasonable complexity.
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abstract the phenomenon of entropy concentration provides strong support for the maximum entropy method, maxent, for inferring a probability vector from information in the form of constraints. here we extend this phenomenon, in a discrete setting, to non-negative integral vectors not necessarily summing to 1. we show that linear constraints that simply bound the allowable sums suffice for concentration to occur even in this setting. this requires a new, ‘generalized’ entropy measure in which the sum of the vector plays a role. we measure the concentration in terms of deviation from the maximum generalized entropy value, or in terms of the distance from the maximum generalized entropy vector. we provide non-asymptotic bounds on the concentration in terms of various parameters, including a tolerance on the constraints which ensures that they are always satisfied by an integral vector. generalized entropy maximization is not only compatible with ordinary maxent, but can also be considered an extension of it, as it allows us to address problems that cannot be formulated as maxent problems.
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abstract our purpose in this study was to present an integral-transform approach to the analytical solutions of the pennes' bioheat transfer equation and to apply it to the calculation of temperature distribution in tissues in hyperthermia with magnetic nanoparticles (magnetic hyperthermia). the validity of our method was investigated by comparison with the analytical solutions obtained by the green's function method for point and shell heat sources and the numerical solutions obtained by the finite-difference method for gaussian-distributed and step-function sources. there was good agreement between the radial profiles of temperature calculated by our method and those obtained by the green's function method. there was also good agreement between our method and the finite-difference method except for the central temperature for a step-function source that had approximately a 0.3% difference. we also found that the equations describing the steady-state solutions for point and shell sources obtained by our method agreed with those obtained by the green’s function method. these results appear to indicate the validity of our method. in conclusion, we presented an integral-transform approach to the bioheat transfer problems in magnetic hyperthermia, and this study demonstrated the validity of our method. the analytical solutions presented in this study will be useful for gaining some insight into the heat diffusion process during magnetic hyperthermia, for testing numerical codes and/or more 2
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abstract—in this paper, we address the problem of the distributed multi-target tracking with labeled set filters in the framework of generalized covariance intersection (gci). our analyses show that the label space mismatching (ls-dm) phenomenon, which means the same realization drawn from label spaces of different sensors does not have the same implication, is quite common in practical scenarios and may bring serious problems. our contributions are two-fold. firstly, we provide a principled mathematical definition of “label spaces matching (lsdm)” based on information divergence, which is also referred to as ls-m criterion. then, to handle the ls-dm, we propose a novel two-step distributed fusion algorithm, named as gci fusion via label spaces matching (gci-lsm). the first step is to match the label spaces from different sensors. to this end, we build a ranked assignment problem and design a cost function consistent with ls-m criterion to seek the optimal solution of matching correspondence between label spaces of different sensors. the second step is to perform the gci fusion on the matched label space. we also derive the gci fusion with generic labeled multiobject (lmo) densities based on ls-m, which is the foundation of labeled distributed fusion algorithms. simulation results for gaussian mixture implementation highlight the performance of the proposed gci-lsm algorithm in two different tracking scenarios.
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abstract. we answer a question of celikbas, dao, and takahashi by establishing the following characterization of gorenstein rings: a commutative noetherian local ring (r, m) is gorenstein if and only if it admits an integrally closed m-primary ideal of finite gorenstein dimension. this is accomplished through a detailed study of certain test complexes. along the way we construct such a test complex that detect finiteness of gorenstein dimension, but not that of projective dimension.
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abstraction, in which the high-level representations can amplify aspects of the input that are important for discrimination. these techniques have been used amongst others to identify network threats [17] or encrypted traffic on a network [18] [19]. a convolutional neural network (cnn), is a specialised architecture of ann that employs a convolution operation in at least one of its layers [20] [21]. a variety of substantiated cnn architectures have been used to great effect in computer vision [22] and even natural language processing (nlp), with empirically distinguished superiority in semantic matching [23], compared to other models. cryptoknight is developed in coordination with this methodology. we introduce a scalable learning system that can easily incorporate new samples through the scalable synthesis of customisable cryptographic algorithms. its entirely automated core architecture is aimed to minimise human interaction, thus allowing the composition of an effective model. we tested the framework on a number of externally sourced applications utilising non-library linked functionality. our experimental analysis indicates that cryptoknight is a flexible solution that can quickly learn from new cryptographic execution patterns to classify unknown software. this manuscript presents the following contributions: • our unique convolutional neural network architecture fits variable-length data to map an application’s timeinvariant cryptographic execution. • complimented by procedural synthesis, we address the issue of this task’s disproportionate latent feature space. • the realised framework, cryptoknight, has demonstrably faster results compared to that of previous methodologies, and is extensively re-trainable. ii. r elated w ork the cryptovirological threat model has rapidly evolved over the last decade. a number of notable individuals and research groups have attempted to address the problem of cryptographic primitive identification. we will discuss the consequences of their findings here and address intrinsic problems. a. heuristics heuristical methods [24] are often utilised to locate an optimal strategy for capturing the most appropriate solution. these measures have previously shown great success in cryptographic primitive identification. a joint project from eth zürich and google, inc. [8] detailed the automated decryption of encrypted network communication in memory, to identify the location and time a subject binary interacted with decrypted input. from an execution trace which dynamically extracted memory access patterns and control flow data [8], was able to identify the necessary factors required to retrieve the relevant data in a new process. his implementation was
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abstract goal recognition is the problem of inferring the goal of an agent, based on its observed actions. an inspiring approach—plan recognition by planning (prp)—uses off-the-shelf planners to dynamically generate plans for given goals, eliminating the need for the traditional plan library. however, existing prp formulation is inherently inefficient in online recognition, and cannot be used with motion planners for continuous spaces. in this paper, we utilize a different prp formulation which allows for online goal recognition, and for application in continuous spaces. we present an online recognition algorithm, where two heuristic decision points may be used to improve run-time significantly over existing work. we specify heuristics for continuous domains, prove guarantees on their use, and empirically evaluate the algorithm over n hundreds of experiments in both a 3d navigational environment and a cooperative robotic team task.
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abstract remote sensing satellite data offer the unique possibility to map land use land cover transformations by providing spatially explicit information. however, detection of short-term processes and land use patterns of high spatial-temporal variability is a challenging task. we present a novel framework using multi-temporal terrasar-x data and machine learning techniques, namely discriminative markov random fields with spatio-temporal priors, and import vector machines, in order to advance the mapping of land cover characterized by short-term changes. our study region covers a current deforestation frontier in the brazilian state pará with land cover dominated by primary forests, different types of pasture land and secondary vegetation, and land use dominated by short-term processes such as slash-and-burn activities. the data set comprises multi-temporal terrasar-x imagery acquired over the course of the 2014 dry season, as well as optical data (rapideye, landsat) for reference. results show that land use land cover is reliably mapped, resulting in spatially adjusted overall accuracies of up to 79% in a five class setting, yet limitations for the differentiation of different pasture types remain. the proposed method is applicable on multi-temporal data sets, and constitutes a feasible approach to map land use land cover in regions that are affected by high-frequent temporal changes. keywords: markov random fields (mrf), import vector machines (ivm), multi-temporal lulc mapping, deforestation, amazon, sar
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abstract for undirected graphs g  (v, e) and g0  (v0 , e0 ), say that g is a region intersection graph over g0 if there is a family of connected subsets {r u ⊆ v0 : u ∈ v } of g0 such that {u, v} ∈ e ⇐⇒ r u ∩ r v , ∅. we show if g0 excludes the complete graph k h as a minor for some h > 1, then every region √ intersection graph g over g0 with m edges has a balanced separator with at most c h m nodes, where c h is a constant depending only on h. if g additionally has uniformly bounded vertex degrees, then such a separator is found by spectral partitioning. a string graph is the intersection graph of continuous arcs in the plane. string graphs are precisely region intersection graphs over planar graphs. thus the preceding result implies that √ every string graph with m edges has a balanced separator of size o( m). this bound is optimal, as it generalizes the planar separator theorem. it confirms a conjecture of fox and pach (2010), √ and improves over the o( m log m) bound of matoušek (2013).
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abstract cell search is the process for a user to detect its neighboring base stations (bss) and make a cell selection decision. due to the importance of beamforming gain in millimeter wave (mmwave) and massive mimo cellular networks, the directional cell search delay performance is investigated. a cellular network with fixed bs and user locations is considered, so that strong temporal correlations exist for the sinr experienced at each bs and user. for poisson cellular networks with rayleigh fading channels, a closed-form expression for the spatially averaged mean cell search delay of all users is derived. this mean cell search delay for a noise-limited network (e.g., mmwave network) is proved to be infinite whenever the non-line-of-sight (nlos) path loss exponent is larger than 2. for interferencelimited networks, a phase transition for the mean cell search delay is shown to exist in terms of the number of bs antennas/beams m : the mean cell search delay is infinite when m is smaller than a threshold and finite otherwise. beam-sweeping is also demonstrated to be effective in decreasing the cell search delay, especially for the cell edge users.
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abstract
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abstract. we deduce properties of the koopman representation of a positive entropy probability measurepreserving action of a countable, discrete, sofic group. our main result may be regarded as a “representationtheoretic” version of sinaı̌’s factor theorem. we show that probability measure-preserving actions with completely positive entropy of an infinite sofic group must be mixing and, if the group is nonamenable, have spectral gap. this implies that if γ is a nonamenable group and γ y (x, µ) is a probability measurepreserving action which is not strongly ergodic, then no action orbit equivalent to γ y (x, µ) has completely positive entropy. crucial to these results is a formula for entropy in the presence of a polish, but a priori noncompact, model.
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abstraction and systems language design c. jasson casey∗ , andrew sutton† , gabriel dos reis† , alex sprintson∗ ∗ department
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abstract we discuss actions of free groups on the circle with “ping-pong” dynamics; these are dynamics determined by a finite amount of combinatorial data, analogous to schottky domains or markov partitions. using this, we show that the free group fn admits an isolated circular order if and only if n is even, in stark contrast with the case for linear orders. this answers a question from [21]. inspired by work in [2], we also exhibit examples of “exotic” isolated points in the space of all circular orders on f2 . analogous results are obtained for linear orders on the groups fn × z.1
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abstract we present a procedure for computing the convolution of exponential signals without the need of solving integrals or summations. the procedure requires the resolution of a system of linear equations involving vandermonde matrices. we apply the method to solve ordinary differential/difference equations with constant coefficients.
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abstract—secure multi-party computation (mpc) enables a set of mutually distrusting parties to cooperatively compute, using a cryptographic protocol, a function over their private data. this paper presents w ys? , a new domain-specific language (dsl) implementation for writing mpcs. w ys? is a verified, domain-specific integrated language extension (vdsile), a new kind of embedded dsl hosted in f? , a fullfeatured, verification-oriented programming language. w ys? source programs are essentially f? programs written against an mpc library, meaning that programmers can use f? ’s logic to verify the correctness and security properties of their programs. to reason about the distributed semantics of these programs, we formalize a deep embedding of w ys? , also in f? . we mechanize the necessary metatheory to prove that the properties verified for the w ys? source programs carry over to the distributed, multi-party semantics. finally, we use f? ’s extraction mechanism to extract an interpreter that we have proved matches this semantics, yielding a verified implementation. w ys? is the first dsl to enable formal verification of source mpc programs, and also the first mpc dsl to provide a verified implementation. with w ys? we have implemented several mpc protocols, including private set intersection, joint median, and an mpc-based card dealing application, and have verified their security and correctness.
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abstract antifragile systems grow measurably better in the presence of hazards. this is in contrast to fragile systems which break down in the presence of hazards, robust systems that tolerate hazards up to a certain degree, and resilient systems that – like selfhealing systems – revert to their earlier expected behavior after a period of convalescence. the notion of antifragility was introduced by taleb for economics systems, but its applicability has been illustrated in biological and engineering domains as well. in this paper, we propose an architecture that imparts antifragility to intelligent autonomous systems, specifically those that are goal-driven and based on ai-planning. we argue that this architecture allows the system to self-improve by uncovering new capabilities obtained either through the hazards themselves (opportunistic) or through deliberation (strategic). an ai planning-based case study of an autonomous wheeled robot is presented. we show that with the proposed architecture, the robot develops antifragile behaviour with respect to an oil spill hazard.
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abstract the objective of clustering is to discover natural groups in datasets and to identify geometrical structures which might reside there, without assuming any prior knowledge on the characteristics of the data. the problem can be seen as detecting the inherent separations between groups of a given point set in a metric space governed by a similarity function. the pairwise similarities between all data objects form a weighted graph adjacency matrix which contains all necessary information for the clustering process, which can consequently be formulated as a graph partitioning problem. in this context, we propose a new cluster quality measure which uses the maximum spanning tree and allows us to compute the optimal clustering under the min-max principle in polynomial time. our algorithm can be applied when a load-balanced clustering is required.
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abstract. we investigate a possible connection between the f sz properties of a group and its sylow subgroups. we show that the simple groups g2 (5) and s6 (5), as well as all sporadic simple groups with order divisible by 56 are not f sz, and that neither are their sylow 5-subgroups. the groups g2 (5) and hn were previously established as non-f sz by peter schauenburg; we present alternative proofs. all other sporadic simple groups and their sylow subgroups are shown to be f sz. we conclude by considering all perfect groups available through gap with order at most 106 , and show they are non-f sz if and only if their sylow 5-subgroups are non-f sz.
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abstract while most scene flow methods use either variational optimization or a strong rigid motion assumption, we show for the first time that scene flow can also be estimated by dense interpolation of sparse matches. to this end, we find sparse matches across two stereo image pairs that are detected without any prior regularization and perform dense interpolation preserving geometric and motion boundaries by using edge information. a few iterations of variational energy minimization are performed to refine our results, which are thoroughly evaluated on the kitti benchmark and additionally compared to state-of-the-art on mpi sintel. for application in an automotive context, we further show that an optional ego-motion model helps to boost performance and blends smoothly into our approach to produce a segmentation of the scene into static and dynamic parts.
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abstract we investigate the problem of testing the equivalence between two discrete histograms. a k-histogram over [n] is a probability distribution that is piecewise constant over some set of k intervals over [n]. histograms have been extensively studied in computer science and statistics. given a set of samples from two k-histogram distributions p, q over [n], we want to distinguish (with high probability) between the cases that p = q and kp − qk1 ≥ ǫ. the main contribution of this paper is a new algorithm for this testing problem and a nearly matching informationtheoretic lower bound. specifically, the sample complexity of our algorithm matches our lower bound up to a logarithmic factor, improving on previous work by polynomial factors in the relevant parameters. our algorithmic approach applies in a more general setting and yields improved sample upper bounds for testing closeness of other structured distributions as well.
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abstract haskell provides type-class-bounded and parametric polymorphism as opposed to subtype polymorphism of object-oriented languages such as java and ocaml. it is a contentious question whether haskell 98 without extensions, or with common extensions, or with new extensions can fully support conventional object-oriented programming with encapsulation, mutable state, inheritance, overriding, statically checked implicit and explicit subtyping, and so on. in a first phase, we demonstrate how far we can get with object-oriented functional programming, if we restrict ourselves to plain haskell 98. in the second and major phase, we systematically substantiate that haskell 98, with some common extensions, supports all the conventional oo features plus more advanced ones, including first-class lexically scoped classes, implicitly polymorphic classes, flexible multiple inheritance, safe downcasts and safe co-variant arguments. haskell indeed can support width and depth, structural and nominal subtyping. we address the particular challenge to preserve haskell’s type inference even for objects and object-operating functions. advanced type inference is a strength of haskell that is worth preserving. many of the features we get “for free”: the type system of haskell turns out to be a great help and a guide rather than a hindrance. the oo features are introduced in haskell as the oohaskell library, non-trivially based on the hlist library of extensible polymorphic records with first-class labels and subtyping. the library sample code, which is patterned after the examples found in oo textbooks and programming language tutorials, including the ocaml object tutorial, demonstrates that oo code translates into oohaskell in an intuition-preserving way: essentially expression-by-expression, without requiring global transformations. oohaskell lends itself as a sandbox for typed oo language design. keywords: object-oriented functional programming, object type inference, typed objectoriented language design, heterogeneous collections, ml-art, mutable objects, typeclass-based programming, haskell, haskell 98, structural subtyping, duck typing, nominal subtyping, width subtyping, deep subtyping, co-variance
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abstract we refine the general methodology in [1] for the construction and analysis of essentially minimax estimators for a wide class of functionals of finite dimensional parameters, and elaborate on the case of discrete distributions with support size s comparable with the number of observations n. specifically, we determine the “smooth” and “non-smooth” regimes based on the confidence set and the smoothness of the functional. in the “non-smooth” regime, we apply an unbiased estimator for a suitable polynomial approximation of the functional. in the “smooth” regime, we construct a general version of the bias-corrected maximum likelihood estimator (mle) based on taylor expansion. we apply the general methodology to the problem of estimating the kl divergence between two discrete probability measures p and q from empirical data in a non-asymptotic and possibly large alphabet setting. we construct minimax rate-optimal estimators for d(p kq) when the likelihood ratio is upper bounded by a constant which may depend on the support size, and show that the performance of the optimal estimator with n samples is essentially that of the mle with n ln n samples. our estimator is adaptive in the sense that it does not require the knowledge of the support size nor the upper bound on the likelihood ratio. we show that the general methodology results in minimax rate-optimal estimators for other divergences as well, such as the hellinger distance and the χ2 -divergence. our approach refines the approximation methodology recently developed for the construction of near minimax estimators of functionals of high-dimensional parameters, such as entropy, rényi entropy, mutual information and `1 distance in large alphabet settings, and shows that the effective sample size enlargement phenomenon holds significantly more widely than previously established. index terms divergence estimation, kl divergence, multivariate approximation theory, taylor expansion, functional estimation, maximum likelihood estimator, high dimensional statistics, minimax lower bound
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