Coalgebraic Communication Protocols and Session Types (YR-OWLS)

Abstract: This is joint work with Alex Keizer and Jorge A. Pérez.

Compositional methods are central to the development and verification of software systems. They allow to break down large systems into smaller components, while enabling reasoning about the behaviour of the composed system. For concurrent and communicating systems, compositional techniques based on *behavioural type systems* have received much attention. By abstracting communication protocols as types, these type systems can statically check that programs interact with channels according to a certain protocol, whether the intended messages are exchanged in a certain order. For this talk, we will put on our coalgebraic spectacles to investigate *session types*, a widely studied class of behavioral type systems. We will seek a syntax-free description of session-based concurrency as states of coalgebras. The result will be a description of type equivalence, duality, and subtyping relations in terms of canonical coinductive presentations. In turn, this coinductive presentation makes it possible to elegantly derive a decidable type system with subtyping for π-calculus processes, in which the states of a coalgebra will serve as channel protocols. Going full circle, we will also exhibit a coalgebra structure on an existing session type system, and show that the relations and type system resulting from our coalgebraic perspective agree with the existing ones.

formal languages and automata theorylogic in computer sciencelogic

Audience: researchers in the discipline

Online Worldwide Seminar on Logic and Semantics (OWLS)

Series comments: The Online Worldwide Seminar on Logic and Semantics is a new series of research talks, highlighting the most exciting recent work in the international computer science logic community. The scope of the seminar series is roughly that of the major computer science logic conferences such as LICS, ICALP and FSCD. It takes place on most Wednesdays, with a focus every other week on the work of young researchers.

In this time of restricted international travel, a key aim of this series is to provide a forum for the informal discussion and social interaction that is so important for the progress of science. To facilitate this, the seminar incorporates in virtual form a number of features more normally associated with physical meetings.

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