We present a sound and complete proof technique, based on syntactic logical relations, for
showing contextual equivalence of expressions in a λ-calculus with recursive types and …

Mitchell's notion of representation independence is a particularly useful application of
Reynolds' relational parametricity--two different implementations of an abstract data type can …

We present a model of recursive and impredicatively quantified types with mutable
references. We interpret in this model all of the type constructors needed for typed …

Subtyping relations are usually defined either syntactically by a formal system or
semantically by an interpretation of types into an untyped denotational model. This work …

Over the last decade, there has been extensive research on modelling challenging features
in programming languages and program logics, such as higher-order store and storable …

Appel and McAllester's" step-indexed" logical relations have proven to be a simple and
effective technique for reasoning about programs in languages with semantically interesting …

We show how to reason about" step-indexed" logical relations in an abstract way, avoiding
the tedious, error-prone, and proof-obscuring step-index arithmetic that seems superficially …

An old and celebrated analogy says that writing programs is like proving theorems. This
analogy has been productive in both directions, but in particular has demonstrated …

We present a typing system with non-idempotent intersection types, typing a term syntax
covering three different calculi: the pure λ-calculus, the calculus with explicit substitutions λ …

The method of logical relations is a classic technique for proving the equivalence of higher-
order programs that implement the same observable behavior but employ different internal …