Relational reasoning for recursive types and references

We present a local relational reasoning method for reasoning about contextual equivalence of expressions in a λ-calculus with recursive types and general references. Our development builds on the work of Benton and Leperchey, who devised a nominal semantics and a local relational reasoning method for a language with simple types and simple references. Their method uses a parameterized logical relation. Here we extend their approach to recursive types and general references. For the extension, we build upon Pitts ’ and Shinwell’s work on relational reasoning about recursive types (but no references) in nominal semantics. The extension is non-trivial because of general references (higher-order store) and makes use of some new ideas for proving the existence of the parameterized logical relation and for the choice of parameters