Logical equivalence for subtyping object and recursive types
Subtyping in first order object calculi is studied with respect to the logical semantics obtained by identifying terms that satisfy the same set of predicates, as formalised through an assignment system. It is shown that equality in the full first order zeta-calculus is modelled by this notion, which in turn is included in a Morris-style contextual equivalence.
object calculi type theory program logic