Speaker: Diana Costa (LASIGE and DI/FCUL) 

Date: 16th of January 2024, 12h

Venue: Seminar Room of the Mathematics Department

Online: https://videoconf-colibri.zoom.us/j/93344876599?pwd=ejkrZ3FpYkh0NE1YV3NCdGFMOGw3QT09

Title: System F^\mu_\omega with context-free session types

Abstract: We study increasingly expressive type systems, from F^\mu - an extension of the polymorphic lambda calculus with equirecursive types - to F^\mu;_omega - the higher-order polymorphic lambda calculus with equirecursive types and context-free session types. Type equivalence is given by a standard bisimulation defined over a novel labelled transition system for types. Our system subsumes the contractive fragment of F^\mu_\omega as studied in the literature. Decidability results for type equivalence of the various type languages are obtained from the translation of types into objects of an appropriate computational model: finite-state automata, simple grammars and deterministic pushdown automata. We show that type equivalence is decidable for a significant fragment of the type language. We further propose a message-passing, concurrent functional language equipped with the expressive type language and show that it enjoys preservation and absence of runtime errors for typable processes. (Joint work with Andreia Mordido and Vasco T. Vasconcelos)