Jar.Consensus.chainMetric (chain : ChainAncestry) (headerHash : Hash)
  (isTicketed : Hash → Bool) : Nat
Jar.Consensus.chainMetric
  (chain : ChainAncestry)
  (headerHash : Hash)
  (isTicketed : Hash → Bool) : Nat

Best chain metric: count of ticketed (non-fallback) seals among ancestors. GP §19. m = Σ_{H^A ∈ A♭} T^A. Select B♭ to maximize this value.

Jar.Consensus.isAcceptable (chain : ChainAncestry)
  (headerHash finalizedHash : Hash) (isAudited : Bool) : Bool
Jar.Consensus.isAcceptable
  (chain : ChainAncestry)
  (headerHash finalizedHash : Hash)
  (isAudited : Bool) : Bool

Check if a block is acceptable for best chain consideration. GP §19. A block must:

1. Be a descendant of the finalized block: A(H♭) ∋ H♮

2. Have all reports audited: U♭ ≡ ⊤

3. Not contain equivocating headers in unfinalized range: ¬∃ H^A ≠ H^B : H^A_T = H^B_T ∧ H^A ∈ A(H♭) ∧ H^A ∉ A(H♮)