,
Andreia Mordido
,
Vasco T. Vasconcelos
Creative Commons Attribution 4.0 International license
Context-free session types describe structured patterns of communication on heterogeneously typed channels, allowing the specification of protocols unconstrained by tail recursion. The enhanced expressive power provided by non-regular recursion comes, however, at the cost of the decidability of subtyping, even if equivalence is still decidable. We present an approach to subtyping context-free session types based on a novel kind of observational preorder we call XYZW-simulation, which generalizes XY-simulation (also known as covariant-contravariant simulation) and therefore also bisimulation and plain simulation. We further propose a subtyping algorithm that we prove to be sound, and present an empirical evaluation in the context of a compiler for a programming language. Due to the general nature of the simulation relation upon which it is built, this algorithm may also find applications in other domains.
@InProceedings{silva_et_al:LIPIcs.CONCUR.2023.11,
author = {Silva, Gil and Mordido, Andreia and Vasconcelos, Vasco T.},
title = {{Subtyping Context-Free Session Types}},
booktitle = {34th International Conference on Concurrency Theory (CONCUR 2023)},
pages = {11:1--11:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-299-0},
ISSN = {1868-8969},
year = {2023},
volume = {279},
editor = {P\'{e}rez, Guillermo A. and Raskin, Jean-Fran\c{c}ois},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2023.11},
URN = {urn:nbn:de:0030-drops-190055},
doi = {10.4230/LIPIcs.CONCUR.2023.11},
annote = {Keywords: Session types, Subtyping, Simulation, Simple grammars, Non-regular recursion}
}