,
Jules Chouquet
,
Axel Kerinec
Creative Commons Attribution 4.0 International license
Approximation semantics capture the observable behaviour of λ-terms. Böhm Trees and Taylor Expansion are its two central paradigms, related by the Commutation Theorem. While these notions are well understood in Call-by-Name (CbN), they have only recently been developed for Call-by-Value (CbV), which motivate the search for a unified approximation framework. The Bang-calculus provides such a framework: it subsumes both CbN and CbV through linear-logic translations and enjoys robust rewriting properties. We develop the approximation semantics of dBang (the Bang-calculus with explicit substitutions and distant reductions) by introducing approximation trees in the Böhm tradition together with Taylor expansion. We establish their fundamental properties, including a commutation theorem. Via translations, our results recover the CbN and CbV cases within a single unifying framework capturing infinitary and resource-sensitive semantics.
@InProceedings{chardonnet_et_al:LIPIcs.FSCD.2026.11,
author = {Chardonnet, Kostia and Chouquet, Jules and Kerinec, Axel},
title = {{Approximation Theory for Distant Bang Calculus}},
booktitle = {11th International Conference on Formal Structures for Computation and Deduction (FSCD 2026)},
pages = {11:1--11:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-433-8},
ISSN = {1868-8969},
year = {2026},
volume = {378},
editor = {Pfenning, Frank},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2026.11},
URN = {urn:nbn:de:0030-drops-263612},
doi = {10.4230/LIPIcs.FSCD.2026.11},
annote = {Keywords: Lambda-calculus, B\"{o}hm Trees, Taylor expansion of lambda-terms}
}