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Documents authored by Vasconcelos, Vasco T.

Found 3 Possible Name Variants:

Vasconcelos, Vasco T.

Document
DOI: 10.4230/LIPIcs.CONCUR.2023.11
Subtyping Context-Free Session Types

Authors: Gil Silva, Andreia Mordido, and Vasco T. Vasconcelos

Published in: LIPIcs, Volume 279, 34th International Conference on Concurrency Theory (CONCUR 2023)

Abstract
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.
Cite as

Gil Silva, Andreia Mordido, and Vasco T. Vasconcelos. Subtyping Context-Free Session Types. In 34th International Conference on Concurrency Theory (CONCUR 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 279, pp. 11:1-11:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@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}
}
Document
DOI: 10.4230/LIPIcs.ECOOP.2018.13
Dependent Types for Class-based Mutable Objects

Authors: Joana Campos and Vasco T. Vasconcelos

Published in: LIPIcs, Volume 109, 32nd European Conference on Object-Oriented Programming (ECOOP 2018)

Abstract
We present an imperative object-oriented language featuring a dependent type system designed to support class-based programming and inheritance. Programmers implement classes in the usual imperative style, and may take advantage of a richer dependent type system to express class invariants and restrictions on how objects are allowed to change and be used as arguments to methods. By way of example, we implement insertion and deletion for binary search trees in an imperative style, and come up with types that ensure the binary search tree invariant. This is the first dependently-typed language with mutable objects that we know of to bring classes and index refinements into play, enabling types (classes) to be refined by indices drawn from some constraint domain. We give a declarative type system that supports objects whose types may change, despite being sound. We also give an algorithmic type system that provides a precise account of quantifier instantiation in a bidirectional style, and from which it is straightforward to read off an implementation. Moreover, all the examples in the paper have been run, compiled and executed in a fully functional prototype that includes a plugin for the Eclipse IDE.
Cite as

Joana Campos and Vasco T. Vasconcelos. Dependent Types for Class-based Mutable Objects. In 32nd European Conference on Object-Oriented Programming (ECOOP 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 109, pp. 13:1-13:28, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@InProceedings{campos_et_al:LIPIcs.ECOOP.2018.13,
  author =	{Campos, Joana and Vasconcelos, Vasco T.},
  title =	{{Dependent Types for Class-based Mutable Objects}},
  booktitle =	{32nd European Conference on Object-Oriented Programming (ECOOP 2018)},
  pages =	{13:1--13:28},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-079-8},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{109},
  editor =	{Millstein, Todd},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2018.13},
  URN =		{urn:nbn:de:0030-drops-92182},
  doi =		{10.4230/LIPIcs.ECOOP.2018.13},
  annote =	{Keywords: dependent types, index refinements, mutable objects, type systems}
}
Document
DOI: 10.4230/DARTS.4.3.1
Dependent Types for Class-based Mutable Objects (Artifact)

Authors: Joana Campos and Vasco T. Vasconcelos

Published in: DARTS, Volume 4, Issue 3, Special Issue of the 32nd European Conference on Object-Oriented Programming (ECOOP 2018)

Abstract
This artifact is based on DOL, a Dependent Object-oriented Language featuring dependent types, mutable objects and class-based inheritance with subtyping. The typechecker written in Xtend, a flexible and expressive dialect of Java, is a direct implementation of the algorithmic type system described in the companion paper. It uses a direct interface to Z3 theorem prover via its API for Java. The artifact ships with an IDE developed as an Eclipse plugin based on the Xtext framework.
Cite as

Joana Campos and Vasco T. Vasconcelos. Dependent Types for Class-based Mutable Objects (Artifact). In Special Issue of the 32nd European Conference on Object-Oriented Programming (ECOOP 2018). Dagstuhl Artifacts Series (DARTS), Volume 4, Issue 3, pp. 1:1-1:2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@Article{campos_et_al:DARTS.4.3.1,
  author =	{Campos, Joana and Vasconcelos, Vasco T.},
  title =	{{Dependent Types for Class-based Mutable Objects (Artifact)}},
  pages =	{1:1--1:2},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2018},
  volume =	{4},
  number =	{3},
  editor =	{Campos, Joana and Vasconcelos, Vasco T.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.4.3.1},
  URN =		{urn:nbn:de:0030-drops-92337},
  doi =		{10.4230/DARTS.4.3.1},
  annote =	{Keywords: dependent types, index refinements, mutable objects, type systems}
}
Document
DOI: 10.4230/DagRep.7.1.158
Theory and Applications of Behavioural Types (Dagstuhl Seminar 17051)

Authors: Simon Gay, Vasco T. Vasconcelos, Philip Wadler, and Nobuko Yoshida

Published in: Dagstuhl Reports, Volume 7, Issue 1 (2017)

Abstract
This report documents the programme and the outcomes of Dagstuhl Seminar 17051 "Theory and Applications of Behavioural Types". Behavioural types describe the dynamic aspects of programs, in contrast to data types, which describe the fixed structure of data. Perhaps the most well-known form of behavioural types is session types, which are type-theoretic specifications of communication protocols. More generally, behavioural types include typestate systems, which specify state-dependent availability of operations; choreographies, which specify collective communication behaviour; and behavioural contracts. In recent years, research activity in behavioural types has increased dramatically, in both theoretical and practical directions. Theoretical work has explored new relationships between established behavioural type systems and areas such as linear logic, automata theory, process calculus testing theory, dependent type theory, and model-checking. On the practical side, there are several implementations of programming languages, programming language extensions, software development tools, and runtime monitoring systems, which are becoming mature enough to apply to real-world case studies. The seminar brought together researchers from the established, largely European, research community in behavioural types, and other participants from outside Europe and from related research topics such as effect systems and actor-based languages. The questions that we intended to explore included: - How can we understand the relationships between the foundations of session types in terms of linear logic, automata, denotational models, and other type theories? - How can the scope and applicability of behavioural types be increased by incorporating ideas and approaches from gradual typing and dependent type theory? - What is the relationship, in terms of expressivity and tractability, between behavioural types and other verification techniques such as model-checking? - What are the theoretical and practical obstacles to delivering behavioural types to software developers in a range of mainstream programming languages? - What are the advantages and disadvantages of incorporating behavioural types into standard programming languages or designing new languages directly based on the foundations of session types? - How can we evaluate the effectiveness of behavioural types in programming languages and software development?
Cite as

Simon Gay, Vasco T. Vasconcelos, Philip Wadler, and Nobuko Yoshida. Theory and Applications of Behavioural Types (Dagstuhl Seminar 17051). In Dagstuhl Reports, Volume 7, Issue 1, pp. 158-189, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@Article{gay_et_al:DagRep.7.1.158,
  author =	{Gay, Simon and Vasconcelos, Vasco T. and Wadler, Philip and Yoshida, Nobuko},
  title =	{{Theory and Applications of Behavioural Types (Dagstuhl Seminar 17051)}},
  pages =	{158--189},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2017},
  volume =	{7},
  number =	{1},
  editor =	{Gay, Simon and Vasconcelos, Vasco T. and Wadler, Philip and Yoshida, Nobuko},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.7.1.158},
  URN =		{urn:nbn:de:0030-drops-72497},
  doi =		{10.4230/DagRep.7.1.158},
  annote =	{Keywords: Behavioural Types, Programming Languages, Runtime Verification, Type Systems}
}
Document
DOI: 10.4230/DagSemProc.05081.6
MiKO---Mikado Koncurrent Objects

Authors: Francisco Martins, Liliana Salvador, Vasco T. Vasconcelos, and Luís Lopes

Published in: Dagstuhl Seminar Proceedings, Volume 5081, Foundations of Global Computing (2006)

Abstract
The motivation for the Mikado migration model is to provide programming constructs for controlling code mobility that are as independent as possible from the particular programming language used to program the code. The main idea is to regard a domain (or site, or locality), where mobile code may enter or exit, as a membrane enclosing running processes, and offering services that have to be called for entering or exiting the domain. MiKO---Mikado Koncurrent Objects is a particular instance of this model, where the membrane is explicitly split in two parts: the methods defining the interface, and a process part describing the data for, and the behavior of, the interface. The talk presents the syntax, operational semantics, and type system of MiKO, together with an example. It concludes by briefly mentioning the implementation of a language based on the calculus.
Cite as

Francisco Martins, Liliana Salvador, Vasco T. Vasconcelos, and Luís Lopes. MiKO---Mikado Koncurrent Objects. In Foundations of Global Computing. Dagstuhl Seminar Proceedings, Volume 5081, pp. 1-43, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{martins_et_al:DagSemProc.05081.6,
  author =	{Martins, Francisco and Salvador, Liliana and Vasconcelos, Vasco T. and Lopes, Lu{\'\i}s},
  title =	{{MiKO---Mikado Koncurrent Objects}},
  booktitle =	{Foundations of Global Computing},
  pages =	{1--43},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{5081},
  editor =	{Jos\'{e} Luiz Fiadeiro and Ugo Montanari and Martin Wirsing},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.05081.6},
  URN =		{urn:nbn:de:0030-drops-3014},
  doi =		{10.4230/DagSemProc.05081.6},
  annote =	{Keywords: Global computing, code migration, administrative domains, process calculus}
}

Vasconcelos, Wamberto

Document
DOI: 10.4230/DFU.Vol4.12111.1
Norms in MAS: Definitions and Related Concepts

Authors: Tina Balke, Célia da Costa Pereira, Frank Dignum, Emiliano Lorini, Antonino Rotolo, Wamberto Vasconcelos, and Serena Villata

Published in: Dagstuhl Follow-Ups, Volume 4, Normative Multi-Agent Systems (2013)

Abstract
In this chapter we provide an introductory presentation of normative multi-agent systems (nMAS). The key idea of the chapter is that any definition of nMAS should preliminarily clarify meaning, scope, and function of the concept of norm. On account of this idea, we focus on three definitions and some related requirements for nMAS. For each of such definitions we propose some guidelines for developing nMAS. Second, we suggest how to relate the concept of nMAS to different conceptions of norms and how norms can be used within the systems. Finally, we identify some specific issues that open research questions or that exhibit interesting overlaps with other disciplines.
Cite as

Tina Balke, Célia da Costa Pereira, Frank Dignum, Emiliano Lorini, Antonino Rotolo, Wamberto Vasconcelos, and Serena Villata. Norms in MAS: Definitions and Related Concepts. In Normative Multi-Agent Systems. Dagstuhl Follow-Ups, Volume 4, pp. 1-31, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2013)

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@InCollection{balke_et_al:DFU.Vol4.12111.1,
  author =	{Balke, Tina and da Costa Pereira, C\'{e}lia and Dignum, Frank and Lorini, Emiliano and Rotolo, Antonino and Vasconcelos, Wamberto and Villata, Serena},
  title =	{{Norms in MAS: Definitions and Related Concepts}},
  booktitle =	{Normative Multi-Agent Systems},
  pages =	{1--31},
  series =	{Dagstuhl Follow-Ups},
  ISBN =	{978-3-939897-51-4},
  ISSN =	{1868-8977},
  year =	{2013},
  volume =	{4},
  editor =	{Andrighetto, Giulia and Governatori, Guido and Noriega, Pablo and van der Torre, Leendert W. N.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DFU.Vol4.12111.1},
  URN =		{urn:nbn:de:0030-drops-39983},
  doi =		{10.4230/DFU.Vol4.12111.1},
  annote =	{Keywords: Norms, MAS}
}
Document
DOI: 10.4230/DagSemProc.09121.12
Contract Formation through Preemptive Normative Conflict Resolution

Authors: Wamberto Vasconcelos and Timothy J. Norman

Published in: Dagstuhl Seminar Proceedings, Volume 9121, Normative Multi-Agent Systems (2009)

Abstract
We explore a rule-based formalisation for contracts: the rules capture conditional norms, that is, they describe situations arising during the enactment of a multi-agent system, and norms that arise from these situations. However, such rules may establish conflicting norms, that is, norms which simultaneously prohibit and oblige (or prohibit and permit) agents to perform particular actions. We propose to use a mechanism to detect and resolve normative conflicts in a preemptive fashion: these mechanisms are used to analyse a contract and suggest "amendments" to the clauses of the contract. These amendments narrow down the scope of influence of norms and avoid normative conflicts. Agents propose rules and their amendments, leading to a contract in which no conflicts may arise.
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Wamberto Vasconcelos and Timothy J. Norman. Contract Formation through Preemptive Normative Conflict Resolution. In Normative Multi-Agent Systems. Dagstuhl Seminar Proceedings, Volume 9121, pp. 1-18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

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@InProceedings{vasconcelos_et_al:DagSemProc.09121.12,
  author =	{Vasconcelos, Wamberto and Norman, Timothy J.},
  title =	{{Contract Formation through Preemptive Normative Conflict Resolution}},
  booktitle =	{Normative Multi-Agent Systems},
  pages =	{1--18},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{9121},
  editor =	{Guido Boella and Pablo Noriega and Gabriella Pigozzi and Harko Verhagen},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.09121.12},
  URN =		{urn:nbn:de:0030-drops-19207},
  doi =		{10.4230/DagSemProc.09121.12},
  annote =	{Keywords: Normative Conflict, Contracts}
}

Vasconcelos, Pedro

Document
DOI: 10.4230/OASIcs.ICPEC.2023.12
Haskelite: A Step-By-Step Interpreter for Teaching Functional Programming

Authors: Pedro Vasconcelos

Published in: OASIcs, Volume 112, 4th International Computer Programming Education Conference (ICPEC 2023)

Abstract
This paper describes Haskelite, a step-by-step interpreter for a small subset of Haskell. Haskelite is designed to help teach fundamental concepts of functional programming, namely: evaluation by rewriting; definition of functions using pattern-matching; recursion; higher-order functions; and on-demand evaluation. The interpreter is implemented in Elm and compiled to JavaScript, so it runs on the browser and requires no installation. This is on-going work and has yet to be fully evaluated; we present some initial experience in the classroom and highlight some points for improvement.
Cite as

Pedro Vasconcelos. Haskelite: A Step-By-Step Interpreter for Teaching Functional Programming. In 4th International Computer Programming Education Conference (ICPEC 2023). Open Access Series in Informatics (OASIcs), Volume 112, pp. 12:1-12:8, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{vasconcelos:OASIcs.ICPEC.2023.12,
  author =	{Vasconcelos, Pedro},
  title =	{{Haskelite: A Step-By-Step Interpreter for Teaching Functional Programming}},
  booktitle =	{4th International Computer Programming Education Conference (ICPEC 2023)},
  pages =	{12:1--12:8},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-290-7},
  ISSN =	{2190-6807},
  year =	{2023},
  volume =	{112},
  editor =	{Peixoto de Queir\'{o}s, Ricardo Alexandre and Teixeira Pinto, M\'{a}rio Paulo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ICPEC.2023.12},
  URN =		{urn:nbn:de:0030-drops-185080},
  doi =		{10.4230/OASIcs.ICPEC.2023.12},
  annote =	{Keywords: Functional programming, Step-by-step evaluators, Web applications}
}
Document
DOI: 10.4230/OASIcs.ICPEC.2020.28
Using Property-Based Testing to Generate Feedback for C Programming Exercises

Authors: Pedro Vasconcelos and Rita P. Ribeiro

Published in: OASIcs, Volume 81, First International Computer Programming Education Conference (ICPEC 2020)

Abstract
This paper reports on the use of property-based testing for providing feedback to C programming exercises. Test cases are generated automatically from properties specified in a test script; this not only makes it possible to conduct many tests (thus potentially find more mistakes), but also allows simplifying failed tests cases automatically. We present some experimental validation gathered for an introductory C programming course during the fall semester of 2018 that show significant positive correlations between getting feedback during the semester and the student’s results in the final exam. We also discuss some limitations regarding feedback for undefined behaviors in the C language.
Cite as

Pedro Vasconcelos and Rita P. Ribeiro. Using Property-Based Testing to Generate Feedback for C Programming Exercises. In First International Computer Programming Education Conference (ICPEC 2020). Open Access Series in Informatics (OASIcs), Volume 81, pp. 28:1-28:10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{vasconcelos_et_al:OASIcs.ICPEC.2020.28,
  author =	{Vasconcelos, Pedro and Ribeiro, Rita P.},
  title =	{{Using Property-Based Testing to Generate Feedback for C Programming Exercises}},
  booktitle =	{First International Computer Programming Education Conference (ICPEC 2020)},
  pages =	{28:1--28:10},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-153-5},
  ISSN =	{2190-6807},
  year =	{2020},
  volume =	{81},
  editor =	{Queir\'{o}s, Ricardo and Portela, Filipe and Pinto, M\'{a}rio and Sim\~{o}es, Alberto},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ICPEC.2020.28},
  URN =		{urn:nbn:de:0030-drops-123159},
  doi =		{10.4230/OASIcs.ICPEC.2020.28},
  annote =	{Keywords: property-based testing, C language, Haskell language, teaching programming}
}
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