Fairness and communication-based semantics for session-typed languages

Polarized SILL is a programming language that combines functional with session-typed message-passing concurrency. It features general recursion; code and channel transmission; synchronous asynchronous communication. To reason about programs, we develop the first program equivalence framework based on observable communications. We give meaning to programs using an observed communication semantics (OCS). Our OCS support recursion transmission. then communication-based testing equivalences show one of captured by our coincides barbed congruence, canonical notion process equivalence. SILL's operational specified multiset rewriting system. introduce fairness for systems ensure well-defined in presence non-terminating processes, use properties simplify reasoning processes. This work lays foundation observational languages recursion.