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arXiv · 2604.10646

Denotational reasoning for asynchronous multiparty session types

Dylan McDermott·Nobuko Yoshida
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Abstract

We provide the first denotational semantics for asynchronous multiparty session types with precise asynchronous subtyping. Our semantics enables us to reason about asynchronous message-passing, in which message-sending is non-blocking. It enables us to prove the correctness of communication optimisations, in particular, those involving reordering of messages. Our development crucially relies on modelling message-passing as a computational effect. We apply grading, a paradigm for tracking computational effects, to asynchronous message-passing, demonstrating that multiparty session typing can be viewed as an instance of grading. We demonstrate the utility of our model by showing that it forms an adequate denotational semantics for a call-by-value asynchronous message-passing calculus, that ensures communication safety, deadlock-freedom and liveness in the presence of communication optimisations.

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Dylan McDermott, Nobuko Yoshida. 2026-04-12. Denotational reasoning for asynchronous multiparty session types. https://doi.org/10.1007/978-3-032-22723-2_3

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