CMP.10:4.2 - Choose what the representation must distinguish

Define how a stored state represents the abstract object or the observations required of it. State the invariants that make reads meaningful. A sorted array needs an order invariant; an aggregate tree needs each stored aggregate to agree with the segment it represents.

If two source states share one representation, check every required read and continuation. Their equality must preserve the requested answers after the allowed updates. MATH.2 supplies identification under operations. If the representation is deliberately lossy, CMP.8 supplies the approximate answer relation.

Keep consequential identity, multiplicity and ordering. A set removes duplicates; a sequence retains positions. A zero numeric value need not mean an absent relation. An object reference and a copied value respond differently to later mutation.