downgrade-equivalence-claim

Purpose

When full equivalence fails, downgrade to the strongest defensible relation and record what was not preserved.

Input contract

required: [equivalence_claim, preservation_report, counterexamples]
optional: [relation_ladder, scope]
constraints: [each downgrade must name lost structures or operations]

Procedure

1. List failed preservation obligations.
2. Test candidate weaker relations.
3. Select the strongest relation supported and document exclusions.

Output contract

produces: [downgraded_relation, lost_invariants, supporting_mapping, exclusions]
delta_fields: [findings, evidence_updates, uncertainties, decisions]

Quality gates