What are Leader VRF and Block VRF values on Pooltool?

Question

During slot battles or height battles between stake pools, the realtime chain tip on Pooltool displays (B) and (L) for the pool that has a lower "Block" and "Leader" VRF value, respectively. Here is an example of one such instance (height battle).

My question is twofold:

1. What are Block and Leader VRF values?
2. How do they relate to the winners/losers of slot battles and/or height battles?

Answer 1

My crude understanding is:

What is a VFR?

"A Verifiable Random Function (VRF) [MRV99] is the public-key version of a keyed cryptographic hash. Only the holder of the private VRF
key can compute the hash, but anyone with corresponding public key
can verify the correctness of the hash." Ref 1

1. What are Block and Leader VRF values?

In the Leader Log, assigned blocks are chosen by their VRF values or score. The pools with the lowest VFR wins (Andrew Westberg described it as, who can do the lowest Limbo).

2. How do they relate to the winners/losers of slot battles and/or height battles?

In the case of slot or height battles, the pool with the lowest VRF wins. It use to be the case that small pools had a slight advantage for slot/height battles. In the Vasil upgrade (Praos), that is no longer the case Ref 2

The source of truth is the Shelley Ledger Spec.