<p>1.) epoch nonce</p>
<p>2.) pool's vrf key</p>
<p>3.) pool's percentage of overall staked ada</p>
<p>4.) active slots coefficient</p>
<p>All four of these determine if a pool is allowed to mint a block in a given slot (happens once per-second on mainnet). The activeSlotsCoefficient protocol parameter is what determines that we make on average 1 block every 20 seconds. Sometimes more, sometimes less, but on average, 1 every 20 seconds.</p>
<p>See my video about this topic to learn more: <a href="https://youtu.be/M3Xq1qz3ljU" rel="noreferrer">https://youtu.be/M3Xq1qz3ljU</a></p>

CC BY-SA 4.0
2021-06-12T07:17:22.607Z
Thanks, it would be best if the answer was written here, what is evaluated against what, is there a hash with a number of leading zeros like classic PoS?
Scalextrix
CC BY-SA 4.0
2021-06-10T20:26:38.130Z
2021-06-10T20:26:38.130Z
Andrew Westberg - BCSH
<p>As far as I can tell, once some blockchain data is fed into a hash, this creates an epoch nonce that is used to define the slot leaders in that epoch.</p>
<p>How is the nonce used to select slot leaders, and what is slot leadership evaluated against to deliver a block on average every 20 slots?  Why can some slot leaders create a block, and why cant others?</p>
<p>Are inputs like transaction hashes part of the block proposal and acceptance process?  Is there some kind of difficulty/target like in regular PoS?</p>

<block-production>
How is a slot leader actually selected to make a block?
# How is a slot leader actually selected to make a block?

(Asked by: username_0 on 2021-06-10)

As far as I can tell, once some blockchain data is fed into a hash, this creates an epoch nonce that is used to define the slot leaders in that epoch.

How is the nonce used to select slot leaders, and what is slot leadership evaluated against to deliver a block on average every 20 slots? Why can some slot leaders create a block, and why cant others?

Are inputs like transaction hashes part of the block proposal and acceptance process? Is there some kind of difficulty/target like in regular PoS?

**Tags:** block-production

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## 1 answers

### Answer by username_1 on 2021-06-10. Score: 9

1.) epoch nonce

2.) pool's vrf key

3.) pool's percentage of overall staked ada

4.) active slots coefficient

All four of these determine if a pool is allowed to mint a block in a given slot (happens once per-second on mainnet). The activeSlotsCoefficient protocol parameter is what determines that we make on average 1 block every 20 seconds. Sometimes more, sometimes less, but on average, 1 every 20 seconds.

See my video about this topic to learn more: <https://youtu.be/M3Xq1qz3ljU>

> **Comments:**
> **username_0**: Thanks, it would be best if the answer was written here, what is evaluated against what, is there a hash with a number of leading zeros like classic PoS?  

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