Function extract_equivocations 

pub fn extract_equivocations(
    a: &JustifiedConfirmation,
    b: &JustifiedConfirmation,
) -> Vec<EquivocationProof>

Extracts proofs of equivocation from two ConfirmedBlock certificates that finalize different blocks at the same height: one proof for every validator whose own signatures on the two certificates (including their justification chains) contradict each other.

Returns an empty list only if the inputs do not actually conflict (same block, or different chains or heights) or are malformed. For two genuinely conflicting, well-formed certificates the proven validators always hold at least a third of the total weight, because each of the following cases blames a full intersection of two quorums. With the lower confirmation in round r and the higher in round s:

• r == s: every validator in the intersection of the two confirmation quorums double-voted.
• r < s and the higher certificate carries a justification chain: the chain’s links tile all rounds from its grounding round up to s with unlocking-round windows, and the grounding link’s window is unbounded below, so some link’s window contains r. Every validator in that link’s intersection with the lower confirmation quorum violated its lock.
• r < s and the higher certificate instead carries the first-round attestation: every validator in the intersection of the two confirmation quorums confirmed in r while attesting that s is the chain’s first round — a first-round violation.