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Multiparty Session Types: Separation and Encodability Results by Prof. Nobuko Yoshida
December 11, 2025 @ 11:00 am - 5:00 pm
Venue: Bharti501 / Teams link will also be shared
Abstract: Multiparty session types (MPST) are a type discipline for enforcing the structured, deadlock-free communication of concurrent and message-passing programs. Traditional MPST have a limited form of choice in which alternative communication possibilities are offered by a single participant and selected by another. Mixed choice multiparty session types (MCMP) extend the choice construct to include both selections and offers in the same choice. This talk presents a mixed-choice synchronous multiparty session calculus and its typing system, which guarantees communication safety and deadlock-freedom. We then talk of expressiveness of nine subcalculi of the MCMP-calculus by examining their encodability (there exists a good encoding from one to another) and separation (there exists no good encoding from one calculus to another). The highlight is that the binary (2-party) mixed sessions by Casal et al. (2022) are strictly less expressive than the MCMP-calculus.
Joint work with Kirstin Peters appeared in LICS’24 (https://arxiv.org/abs/2405.08104)
About the speaker. Nobuko Yoshida is Christopher Strachey Chair of Computer Science in University of Oxford. She is an EPSRC Established Career Fellow and an Honorary Fellow at Glasgow University. Last 10 years, her main research interests are theories and applications of protocol specification and verification. She introduced multiparty session types [ POPL’08, JACM ] which received the Most Influential POPL Paper Award in 2018 (judged by its influence over the last decade). This work enlarged the community and widened the scope of applications of session types, e.g. runtime monitoring based on Scribble (co-developed with Red Hat) has been deployed to other projects such as cyberinfrastructure in the US Ocean Observatories Initiative (OOI); and widened the scope of her research areas. She received the Test-of-time-award from PPDP’24 and the best paper awards from CC’20, COORDINATION’23 and DisCoTech’23. She received the third Suffrage Science Award for Mathematics and Computing from MRC for her STEM activity. She is an editor of ACM Transactions on Programming Languages and Systems, Theoretical Computer Science, ACM Formal Aspects of Computing, Mathematical Structures in Computer Science, Journal of Logical Algebraic Methods in Programming, and the chief editor of The Computer-aided Verification and Concurrency Column for EATCS Bulletin.