6 Search Results for "McCusker, Guy"

Document
DOI: 10.4230/LIPIcs.CSL.2026.28
Resourceful Traces for Commuting Processes

Authors: Matthew Earnshaw, Chad Nester, and Mario Román

Published in: LIPIcs, Volume 363, 34th EACSL Annual Conference on Computer Science Logic (CSL 2026)

Abstract
We show that, when the actions of a Mazurkiewicz trace are considered not merely as atomic but as transformations from a specified type of inputs to a specified type of outputs, we obtain a novel notion of presentation for effectful categories (also known as generalized Freyd categories), a well-known algebraic structure in the semantics of side-effecting computation. Like the usual representation of traces as graphs, our notion of presentation gives rise to a graphical representation of morphisms in effectful categories. We use our presentations to give a construction of the commuting tensor product of free effectful categories, capturing the combination of systems in which the actions of each must commute with one another, while still permitting exchange of resources.
Cite as

Matthew Earnshaw, Chad Nester, and Mario Román. Resourceful Traces for Commuting Processes. In 34th EACSL Annual Conference on Computer Science Logic (CSL 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 363, pp. 28:1-28:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{earnshaw_et_al:LIPIcs.CSL.2026.28,
  author =	{Earnshaw, Matthew and Nester, Chad and Rom\'{a}n, Mario},
  title =	{{Resourceful Traces for Commuting Processes}},
  booktitle =	{34th EACSL Annual Conference on Computer Science Logic (CSL 2026)},
  pages =	{28:1--28:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-411-6},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{363},
  editor =	{Guerrini, Stefano and K\"{o}nig, Barbara},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2026.28},
  URN =		{urn:nbn:de:0030-drops-254522},
  doi =		{10.4230/LIPIcs.CSL.2026.28},
  annote =	{Keywords: Mazurkiewicz traces, premonoidal categories, monoidal categories, effectful categories}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.CSL.2026.4
Towards A Rosetta Stone of Interactive and Quantitative Semantics (Invited Talk)

Authors: Pierre Clairambault

Published in: LIPIcs, Volume 363, 34th EACSL Annual Conference on Computer Science Logic (CSL 2026)

Abstract
Quantitative semantics are those denotational semantics that inherit from linear logic [Jean-Yves Girard, 1987] a sensitivity to the multiplicity of resources involved in computation. Those include the relational model [Jean-Yves Girard, 1987] and its numerous variations (such as finiteness spaces [Thomas Ehrhard, 2005], weighted relational models [Jim Laird et al., 2013] and their extensions [Thomas Ehrhard et al., 2011; Thomas Ehrhard, 2002], generalized species of structure [Fiore et al., 2008], span models [Paul-André Melliès, 2019; Pierre Clairambault and Simon Forest, 2023], etc), as well as related syntactic methods such as non-idempotent intersection types [Daniel de Carvalho, 2018] and Taylor expansion of lambda-terms [Thomas Ehrhard and Laurent Regnier, 2003]. Interactive semantics are usually also quantitative, but in addition they present the interactive behaviour of proofs and programs, generally organized chronologically - those include the many variants of game semantics (starting with [J. M. E. Hyland and C.-H. Luke Ong, 2000; Samson Abramsky et al., 2000]), and other frameworks such as Geometry of Interaction [Girard, 1989] or ludics [Jean-Yves Girard, 2001]. Both families are cornerstones of modern denotational semantics, and both have associated Alonzo Church awards: game semantics in 2017, and quantitative semantics (in particular, differential linear logic and the differential λ-calculus) in 2024. It has more or less always been clear to the experts that the two, sharing an origin in linear logic, are conceptually related. Yet there are differences, which seem fundamental: in particular, while quantitative models compose relationally, the composition of strategies follows an intricate "parallel interaction plus hiding" process inspired from concurrency theory [Abramsky, 1997]. The two families of models have also historically targeted different kinds of languages: whereas quantitative semantics focused on theoretical calculi (and the λ-calculus in particular), game semantics is known for fully abstract models for languages with elaborate combinations of effects including local state [Samson Abramsky and Guy McCusker, 1996], control operators [James Laird, 1997], and concurrent primitives [Dan R. Ghica and Andrzej S. Murawski, 2008]. Early on, researchers have explored the relationship between the two [Thomas Ehrhard, 1996; Patrick Baillot et al., 1997], and investigations on this question have spanned decades [Pierre Boudes, 2009; Ana C. Calderon and Guy McCusker, 2010; Takeshi Tsukada and C.-H. Luke Ong, 2016; C.-H. Luke Ong, 2017]. In particular, Melliès' work on asynchronous games [Paul-André Melliès, 2006; Paul-André Melliès, 2005] made significant conceptual contributions, showing that the issue was enlightened by adopting a positional formulation of game semantics, where points in the relational model simply arise as certain positions. This talk surveys recent developments in this line of work, shedding light on the connection between those two families. Our work is set in so-called "thin concurrent games" [Simon Castellan et al., 2019; Pierre Clairambault, 2024], an extension with symmetry of Rideau and Winskel’s concurrent games on event structures [Silvain Rideau and Glynn Winskel, 2011]. Event structures being one of the main "truly concurrent" models of concurrency [Glynn Winskel, 1986], it is perhaps expected that thin concurrent games can model concurrent languages: they provide a truly concurrent refinement of Ghica and Murawski’s fully abstract model of Idealized Concurrent Algol [Simon Castellan and Pierre Clairambault, 2024; Pierre Clairambault, 2024]. But beyond the semantics of concurrency, thin concurrent games are also a deep reworking on game semantics built from causal principles, inheriting from asynchronous games a positional flavour. In thin concurrent games, strategies have a dual nature: an event-based nature where they appear as certain event structures composed via parallel interaction plus hiding; or a positional nature where they appear as certain spans of groupoids, composed by pullback (modulo a technical condition on strategies called visibility) - they can be regarded both as a games and a relational model! Leveraging this dual nature, in a sequence of papers with Castellan, de Visme, Olimpieri and Paquet, we have been able to link the single framework of thin concurrent games with numerous other models. This includes various traditional alternating or non-alternating games models [Simon Castellan and Pierre Clairambault, 2024; Pierre Clairambault, 2024], the weighted relational model [Pierre Clairambault and Hugo Paquet, 2021], the quantum relational model [Pierre Clairambault and Marc de Visme, 2020], generalized species of structure [Pierre Clairambault et al., 2023], and - going beyond quantitative semantics - the linear Scott model [Clairambault, 2025], a linear decomposition of standard Scott domain semantics [Thomas Ehrhard, 2012]. All these distinct models are obtained by projecting away certain aspects of thin concurrent games, giving some support to the claim that thin concurrent games are a Rosetta stone for interactive and quantitative semantics.
Cite as

Pierre Clairambault. Towards A Rosetta Stone of Interactive and Quantitative Semantics (Invited Talk). In 34th EACSL Annual Conference on Computer Science Logic (CSL 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 363, pp. 4:1-4:4, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{clairambault:LIPIcs.CSL.2026.4,
  author =	{Clairambault, Pierre},
  title =	{{Towards A Rosetta Stone of Interactive and Quantitative Semantics}},
  booktitle =	{34th EACSL Annual Conference on Computer Science Logic (CSL 2026)},
  pages =	{4:1--4:4},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-411-6},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{363},
  editor =	{Guerrini, Stefano and K\"{o}nig, Barbara},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2026.4},
  URN =		{urn:nbn:de:0030-drops-254286},
  doi =		{10.4230/LIPIcs.CSL.2026.4},
  annote =	{Keywords: Denotational semantics, Game semantics}
}
Document
DOI: 10.4230/LIPIcs.FSCD.2025.6
Weighted Rewriting: Semiring Semantics for Abstract Reduction Systems

Authors: Emma Ahrens, Jan-Christoph Kassing, Jürgen Giesl, and Joost-Pieter Katoen

Published in: LIPIcs, Volume 337, 10th International Conference on Formal Structures for Computation and Deduction (FSCD 2025)

Abstract
We present novel semiring semantics for abstract reduction systems (ARSs). More precisely, we provide a weighted version of ARSs, where the reduction steps induce weights from a semiring. Inspired by provenance analysis in database theory and logic, we obtain a formalism that can be used for provenance analysis of arbitrary ARSs. Our semantics handle (possibly unbounded) non-determinism and possibly infinite reductions. Moreover, we develop several techniques to prove upper and lower bounds on the weights resulting from our semantics, and show that in this way one obtains a uniform approach to analyze several different properties like termination, derivational complexity, space complexity, safety, as well as combinations of these properties.
Cite as

Emma Ahrens, Jan-Christoph Kassing, Jürgen Giesl, and Joost-Pieter Katoen. Weighted Rewriting: Semiring Semantics for Abstract Reduction Systems. In 10th International Conference on Formal Structures for Computation and Deduction (FSCD 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 337, pp. 6:1-6:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{ahrens_et_al:LIPIcs.FSCD.2025.6,
  author =	{Ahrens, Emma and Kassing, Jan-Christoph and Giesl, J\"{u}rgen and Katoen, Joost-Pieter},
  title =	{{Weighted Rewriting: Semiring Semantics for Abstract Reduction Systems}},
  booktitle =	{10th International Conference on Formal Structures for Computation and Deduction (FSCD 2025)},
  pages =	{6:1--6:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-374-4},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{337},
  editor =	{Fern\'{a}ndez, Maribel},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2025.6},
  URN =		{urn:nbn:de:0030-drops-236215},
  doi =		{10.4230/LIPIcs.FSCD.2025.6},
  annote =	{Keywords: Rewriting, Semirings, Semantics, Termination, Verification}
}
Document
DOI: 10.4230/LIPIcs.CSL.2025.31
Simple Types for Probabilistic Termination

Authors: Willem Heijltjes and Georgina Majury

Published in: LIPIcs, Volume 326, 33rd EACSL Annual Conference on Computer Science Logic (CSL 2025)

Abstract
We present a new typing discipline to guarantee the probability of termination in probabilistic lambda-calculi. The main contribution is a particular naturality and simplicity: our probabilistic types are as simple types, but generated from probabilities as base types, representing a least probability of termination. Simple types are recovered by restricting probabilities to one. Our vehicle is the Probabilistic Event Lambda-Calculus by Dal Lago, Guerrieri, and Heijltjes, which presents a solution to the issue of confluence in probabilistic lambda-calculi. Our probabilistic type system provides an alternative solution to that using counting quantifiers by Antonelli, Dal Lago, and Pistone, for the same calculus. The problem that both type systems address is to give a lower bound on the probability that terms head-normalize. Following the recent Functional Machine Calculus by Heijltjes, our development takes the (simplified) Krivine machine as primary, and proceeds via an extension of the calculus with sequential composition and identity on the machine. Our type system then gives a natural account of termination probability on the Krivine machine, reflected back onto head-normalization for the original calculus. In this way we are able to avoid the use of counting quantifiers, while improving on the termination bounds given by Antonelli, Dal Lago, and Pistone.
Cite as

Willem Heijltjes and Georgina Majury. Simple Types for Probabilistic Termination. In 33rd EACSL Annual Conference on Computer Science Logic (CSL 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 326, pp. 31:1-31:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{heijltjes_et_al:LIPIcs.CSL.2025.31,
  author =	{Heijltjes, Willem and Majury, Georgina},
  title =	{{Simple Types for Probabilistic Termination}},
  booktitle =	{33rd EACSL Annual Conference on Computer Science Logic (CSL 2025)},
  pages =	{31:1--31:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-362-1},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{326},
  editor =	{Endrullis, J\"{o}rg and Schmitz, Sylvain},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2025.31},
  URN =		{urn:nbn:de:0030-drops-227885},
  doi =		{10.4230/LIPIcs.CSL.2025.31},
  annote =	{Keywords: lambda-calculus, probabilistic termination, simple types}
}
Document
DOI: 10.4230/LIPIcs.CSL.2023.10
The Functional Machine Calculus II: Semantics

Authors: Chris Barrett, Willem Heijltjes, and Guy McCusker

Published in: LIPIcs, Volume 252, 31st EACSL Annual Conference on Computer Science Logic (CSL 2023)

Abstract
The Functional Machine Calculus (FMC), recently introduced by the second author, is a generalization of the lambda-calculus which may faithfully encode the effects of higher-order mutable store, I/O and probabilistic/non-deterministic input. Significantly, it remains confluent and can be simply typed in the presence of these effects. In this paper, we explore the denotational semantics of the FMC. We have three main contributions: first, we argue that its syntax - in which both effects and lambda-calculus are realised using the same syntactic constructs - is semantically natural, corresponding closely to the structure of a Scott-style domain theoretic semantics. Second, we show that simple types confer strong normalization by extending Gandy’s proof for the lambda-calculus, including a small simplification of the technique. Finally, we show that the typed FMC (without considering the specifics of encoded effects), modulo an appropriate equational theory, is a complete language for Cartesian closed categories.
Cite as

Chris Barrett, Willem Heijltjes, and Guy McCusker. The Functional Machine Calculus II: Semantics. In 31st EACSL Annual Conference on Computer Science Logic (CSL 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 252, pp. 10:1-10:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{barrett_et_al:LIPIcs.CSL.2023.10,
  author =	{Barrett, Chris and Heijltjes, Willem and McCusker, Guy},
  title =	{{The Functional Machine Calculus II: Semantics}},
  booktitle =	{31st EACSL Annual Conference on Computer Science Logic (CSL 2023)},
  pages =	{10:1--10:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-264-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{252},
  editor =	{Klin, Bartek and Pimentel, Elaine},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2023.10},
  URN =		{urn:nbn:de:0030-drops-174716},
  doi =		{10.4230/LIPIcs.CSL.2023.10},
  annote =	{Keywords: lambda-calculus, computational effects, denotational semantics, strong normalization}
}
Document
DOI: 10.4230/LIPIcs.CSL.2018.33
On Compositionality of Dinatural Transformations

Authors: Guy McCusker and Alessio Santamaria

Published in: LIPIcs, Volume 119, 27th EACSL Annual Conference on Computer Science Logic (CSL 2018)

Abstract
Natural transformations are ubiquitous in mathematics, logic and computer science. For operations of mixed variance, such as currying and evaluation in the lambda-calculus, Eilenberg and Kelly's notion of extranatural transformation, and often the even more general dinatural transformation, is required. Unfortunately dinaturals are not closed under composition except in special circumstances. This paper presents a new sufficient condition for composability. We propose a generalised notion of dinatural transformation in many variables, and extend the Eilenberg-Kelly account of composition for extranaturals to these transformations. Our main result is that a composition of dinatural transformations which creates no cyclic connections between arguments yields a dinatural transformation. We also extend the classical notion of horizontal composition to our generalized dinaturals and demonstrate that it is associative and has identities.
Cite as

Guy McCusker and Alessio Santamaria. On Compositionality of Dinatural Transformations. In 27th EACSL Annual Conference on Computer Science Logic (CSL 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 119, pp. 33:1-33:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@InProceedings{mccusker_et_al:LIPIcs.CSL.2018.33,
  author =	{McCusker, Guy and Santamaria, Alessio},
  title =	{{On Compositionality of Dinatural Transformations}},
  booktitle =	{27th EACSL Annual Conference on Computer Science Logic (CSL 2018)},
  pages =	{33:1--33:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-088-0},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{119},
  editor =	{Ghica, Dan R. and Jung, Achim},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2018.33},
  URN =		{urn:nbn:de:0030-drops-97006},
  doi =		{10.4230/LIPIcs.CSL.2018.33},
  annote =	{Keywords: Dinatural transformation, categorical logic, compositionality}
}
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