arXiv subjects

Alceste Scalas

Publications and source records attributed to Alceste Scalas.

25 records · Page 2Linked to original sources

arXiv2020

Proceedings 13th Interaction and Concurrency Experience

This volume contains the proceedings of ICE'20, the 13th Interaction and Concurrency Experience, which was held online on the 19th of June 2020, as a satellite event of DisCoTec'20. The ICE workshop series features a distinguishing review and selection procedure, allowing PC members to interact anonymously with authors. As in the past 12 editions, this interaction considerably improved the accuracy of the feedback from the reviewers and the quality of accepted papers, and offered the basis for lively discussion during the workshop. The 2020 edition of ICE included double blind reviewing of original research papers, in order to increase fairness and avoid bias in reviewing. Each paper was reviewed by three PC members, and altogether 5 papers were accepted for publication - plus 5 oral presentations which are not part of this volume. We were proud to host 2 invited talks, by Cinzia Di Giusto and Karoliina Lehtinen. The abstracts of these talks are included in this volume together with the regular papers. The final versions of the contributions, taking into account the discussion at the workshop, are included.

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arXiv2019

Proceedings 12th Interaction and Concurrency Experience

This volume contains the proceedings of ICE'19, the 12th Interaction and Concurrency Experience, which was held in Copenhagen, Denmark on the 20th and 21st of June 2019, as a satellite event of DisCoTec'19. The ICE workshop series features a distinguishing review and selection procedure, allowing PC members to interact anonymously with authors. As in the past 11 editions, this interaction considerably improved the accuracy of the feedback from the reviewers and the quality of accepted papers, and offered the basis for lively discussion during the workshop. The 2019 edition of ICE included double blind reviewing of original research papers, in order to increase fairness and avoid bias in reviewing. Each paper was reviewed by three PC members, and altogether 9 papers were accepted for publication - plus 2 oral presentations which are not part of this volume. We were proud to host 4 invited talks, by Dilian Gurov, Fritz Henglein, Sophia Knight, and Hernán Melgratti. The abstracts of these talks are included in this volume together with the regular papers. Final versions of the contributions, taking into account the discussion at the workshop, are included.

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arXiv2017

On the Preciseness of Subtyping in Session Types

Subtyping in concurrency has been extensively studied since early 1990s as one of the most interesting issues in type theory. The correctness of subtyping relations has been usually provided as the soundness for type safety. The converse direction, the completeness, has been largely ignored in spite of its usefulness to define the largest subtyping relation ensuring type safety. This paper formalises preciseness (i.e. both soundness and completeness) of subtyping for mobile processes and studies it for the synchronous and the asynchronous session calculi. We first prove that the well-known session subtyping, the branching-selection subtyping, is sound and complete for the synchronous calculus. Next we show that in the asynchronous calculus, this subtyping is incomplete for type-safety: that is, there exist session types T and S such that T can safely be considered as a subtype of S, but T < S is not derivable by the subtyping. We then propose an asynchronous subtyping system which is sound and complete for the asynchronous calculus. The method gives a general guidance to design rigorous channel-based subtypings respecting desired safety properties. Both the synchronous and the asynchronous calculus are first considered with lin ear channels only, and then they are extended with session initialisations and c ommunications of expressions (including shared channels).

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arXiv2017

Multiparty Session Types, Beyond Duality (Abstract)

Multiparty Session Types (MPST) are a well-established typing discipline for message-passing processes interacting on sessions involving two or more participants. Session typing can ensure desirable properties: absence of communication errors and deadlocks, and protocol conformance. However, existing MPST works provide a subject reduction result that is arguably (and sometimes, surprisingly) restrictive: it only holds for typing contexts with strong duality constraints on the interactions between pairs of participants. Consequently, many "intuitively correct" examples cannot be typed and/or cannot be proved type-safe. We illustrate some of these examples, and discuss the reason for these limitations. Then, we outline a novel MPST typing system that removes these restrictions.

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arXiv2016

Honesty by Typing

We propose a type system for a calculus of contracting processes. Processes can establish sessions by stipulating contracts, and then can interact either by keeping the promises made, or not. Type safety guarantees that a typeable process is honest - that is, it abides by the contracts it has stipulated in all possible contexts, even in presence of dishonest adversaries. Type inference is decidable, and it allows to safely approximate the honesty of processes using either synchronous or asynchronous communication.

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arXiv2015

The LTS WorkBench

Labelled Transition Systems (LTSs) are a fundamental semantic model in many areas of informatics, especially concurrency theory. Yet, reasoning on LTSs and relations between their states can be difficult and elusive: very simple process algebra terms can give rise to a large (possibly infinite) number of intricate transitions and interactions. To ease this kind of study, we present LTSwb, a flexible and extensible LTS toolbox: this tutorial paper discusses its design and functionalities.

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arXiv2013

Choreography Synthesis as Contract Agreement

We propose a formal model for distributed systems, where each participant advertises its requirements and obligations as behavioural contracts, and where multiparty sessions are started when a set of contracts allows to synthesise a choreography. Our framework is based on the CO2 calculus for contract-oriented computing, and borrows concepts and results from the session type literature. It supports sessions where the number of participants is not determined beforehand, and keeps CO2's ability to rule out participants that are culpable if contracts are not fulfilled at runtime. We show that we have progress and session fidelity in CO2, as a result of the honesty of participants - i.e., their ability to always adhere to their contracts.

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