15 Search Results for "Castro-Perez, David"

Document
DOI: 10.4230/LIPIcs.MFCS.2023.11
The Geometry of Reachability in Continuous Vector Addition Systems with States

Authors: Shaull Almagor, Arka Ghosh, Tim Leys, and Guillermo A. Pérez

Published in: LIPIcs, Volume 272, 48th International Symposium on Mathematical Foundations of Computer Science (MFCS 2023)

Abstract
We study the geometry of reachability sets of continuous vector addition systems with states (VASS). In particular we establish that they are "almost" Minkowski sums of convex cones and zonotopes generated by the vectors labelling the transitions of the VASS. We use the latter to prove that short so-called linear path schemes suffice as witnesses of reachability in continuous VASS. Then, we give new polynomial-time algorithms for the reachability problem for linear path schemes. Finally, we also establish that enriching the model with zero tests makes the reachability problem intractable already for linear path schemes of dimension two.
Cite as

Shaull Almagor, Arka Ghosh, Tim Leys, and Guillermo A. Pérez. The Geometry of Reachability in Continuous Vector Addition Systems with States. In 48th International Symposium on Mathematical Foundations of Computer Science (MFCS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 272, pp. 11:1-11:13, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@InProceedings{almagor_et_al:LIPIcs.MFCS.2023.11,
  author =	{Almagor, Shaull and Ghosh, Arka and Leys, Tim and P\'{e}rez, Guillermo A.},
  title =	{{The Geometry of Reachability in Continuous Vector Addition Systems with States}},
  booktitle =	{48th International Symposium on Mathematical Foundations of Computer Science (MFCS 2023)},
  pages =	{11:1--11:13},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-292-1},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{272},
  editor =	{Leroux, J\'{e}r\^{o}me and Lombardy, Sylvain and Peleg, David},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2023.11},
  URN =		{urn:nbn:de:0030-drops-185457},
  doi =		{10.4230/LIPIcs.MFCS.2023.11},
  annote =	{Keywords: Vector addition system with states, reachability, continuous approximation}
}
Document
DOI: 10.4230/LIPIcs.MFCS.2023.30
Parikh One-Counter Automata

Authors: Michaël Cadilhac, Arka Ghosh, Guillermo A. Pérez, and Ritam Raha

Published in: LIPIcs, Volume 272, 48th International Symposium on Mathematical Foundations of Computer Science (MFCS 2023)

Abstract
Counting abilities in finite automata are traditionally provided by two orthogonal extensions: adding a single counter that can be tested for zeroness at any point, or adding ℤ-valued counters that are tested for equality only at the end of runs. In this paper, finite automata extended with both types of counters are introduced. They are called Parikh One-Counter Automata (POCA): the "Parikh" part referring to the evaluation of counters at the end of runs, and the "One-Counter" part to the single counter that can be tested during runs. Their expressiveness, in the deterministic and nondeterministic variants, is investigated; it is shown in particular that there are deterministic POCA languages that cannot be expressed without nondeterminism in the original models. The natural decision problems are also studied; strikingly, most of them are no harder than in the original models. A parametric version of nonemptiness is also considered.
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Michaël Cadilhac, Arka Ghosh, Guillermo A. Pérez, and Ritam Raha. Parikh One-Counter Automata. In 48th International Symposium on Mathematical Foundations of Computer Science (MFCS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 272, pp. 30:1-30:15, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@InProceedings{cadilhac_et_al:LIPIcs.MFCS.2023.30,
  author =	{Cadilhac, Micha\"{e}l and Ghosh, Arka and P\'{e}rez, Guillermo A. and Raha, Ritam},
  title =	{{Parikh One-Counter Automata}},
  booktitle =	{48th International Symposium on Mathematical Foundations of Computer Science (MFCS 2023)},
  pages =	{30:1--30:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-292-1},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{272},
  editor =	{Leroux, J\'{e}r\^{o}me and Lombardy, Sylvain and Peleg, David},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2023.30},
  URN =		{urn:nbn:de:0030-drops-185645},
  doi =		{10.4230/LIPIcs.MFCS.2023.30},
  annote =	{Keywords: Parikh automata, Context-free languages, One-counter automata}
}
Document
DOI: 10.4230/LIPIcs.SEA.2023.13
Integer Programming Formulations and Cutting Plane Algorithms for the Maximum Selective Tree Problem

Authors: Ömer Burak Onar, Tınaz Ekim, and Z. Caner Taşkın

Published in: LIPIcs, Volume 265, 21st International Symposium on Experimental Algorithms (SEA 2023)

Abstract
This paper considers the Maximum Selective Tree Problem (MSelTP) as a generalization of the Maximum Induced Tree problem. Given an undirected graph with a partition of its vertex set into clusters, MSelTP aims to choose the maximum number of vertices such that at most one vertex per cluster is selected and the graph induced by the selected vertices is a tree. To the best of our knowledge, MSelTP has not been studied before although several related optimization problems have been investigated in the literature. We propose two mixed integer programming formulations for MSelTP; one based on connectivity constraints, the other based on cycle elimination constraints. In addition, we develop two exact cutting plane procedures to solve the problem to optimality. On graphs with up to 25 clusters, up to 250 vertices, and varying densities, we conduct computational experiments to compare the results of two solution procedures with solving a compact integer programming formulation of MSelTP. Our experiments indicate that the algorithm CPAXnY outperforms the other procedures overall except for graphs with low density and large cluster size, and that the algorithm CPAX yields better results in terms of the average time of instances optimally solved and the overall average time.
Cite as

Ömer Burak Onar, Tınaz Ekim, and Z. Caner Taşkın. Integer Programming Formulations and Cutting Plane Algorithms for the Maximum Selective Tree Problem. In 21st International Symposium on Experimental Algorithms (SEA 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 265, pp. 13:1-13:18, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@InProceedings{onar_et_al:LIPIcs.SEA.2023.13,
  author =	{Onar, \"{O}mer Burak and Ekim, T{\i}naz and Ta\c{s}k{\i}n, Z. Caner},
  title =	{{Integer Programming Formulations and Cutting Plane Algorithms for the Maximum Selective Tree Problem}},
  booktitle =	{21st International Symposium on Experimental Algorithms (SEA 2023)},
  pages =	{13:1--13:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-279-2},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{265},
  editor =	{Georgiadis, Loukas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2023.13},
  URN =		{urn:nbn:de:0030-drops-183634},
  doi =		{10.4230/LIPIcs.SEA.2023.13},
  annote =	{Keywords: maximum induced tree, selective tree, cutting plane, separation algorithm, mixed integer programming}
}
Document
DOI: 10.4230/LIPIcs.ECOOP.2023.6
Dynamically Updatable Multiparty Session Protocols: Generating Concurrent Go Code from Unbounded Protocols

Authors: David Castro-Perez and Nobuko Yoshida

Published in: LIPIcs, Volume 263, 37th European Conference on Object-Oriented Programming (ECOOP 2023)

Abstract
Multiparty Session Types (MPST) are a typing disciplines that guarantee the absence of deadlocks and communication errors in concurrent and distributed systems. However, existing MPST frameworks do not support protocols with dynamic unbounded participants, and cannot express many common programming patterns that require the introduction of new participants into a protocol. This poses a barrier for the adoption of MPST in languages that favour the creation of new participants (processes, lightweight threads, etc) that communicate via message passing, such as Go or Erlang. This paper proposes Dynamically Updatable Multiparty Session Protocols, a new MPST theory (DMst) that supports protocols with an unbounded number of fresh participants, whose communication topologies are dynamically updatable. We prove that DMst guarantees deadlock-freedom and liveness. We implement a toolchain, GoScr (Go-Scribble), which generates Go implementations from DMst, ensuring by construction, that the different participants will only perform I/O actions that comply with a given protocol specification. We evaluate our toolchain by (1) implementing representative parallel and concurrent algorithms from existing benchmarks, textbooks and literature; (2) showing that GoScr does not introduce significant overheads compared to a naive implementation, for computationally expensive benchmarks; and (3) building three realistic protocols (dynamic task delegation, recursive Domain Name System, and a parallel Min-Max strategy) in GoScr that could not be represented with previous theories of session types.
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David Castro-Perez and Nobuko Yoshida. Dynamically Updatable Multiparty Session Protocols: Generating Concurrent Go Code from Unbounded Protocols. In 37th European Conference on Object-Oriented Programming (ECOOP 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 263, pp. 6:1-6:30, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@InProceedings{castroperez_et_al:LIPIcs.ECOOP.2023.6,
  author =	{Castro-Perez, David and Yoshida, Nobuko},
  title =	{{Dynamically Updatable Multiparty Session Protocols: Generating Concurrent Go Code from Unbounded Protocols}},
  booktitle =	{37th European Conference on Object-Oriented Programming (ECOOP 2023)},
  pages =	{6:1--6:30},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-281-5},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{263},
  editor =	{Ali, Karim and Salvaneschi, Guido},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2023.6},
  URN =		{urn:nbn:de:0030-drops-181995},
  doi =		{10.4230/LIPIcs.ECOOP.2023.6},
  annote =	{Keywords: Multiparty Session Types, Correctness-by-construction, Concurrency, Golang}
}
Document
DOI: 10.4230/LIPIcs.FSCD.2023.28
Concurrent Realizability on Conjunctive Structures

Authors: Emmanuel Beffara, Félix Castro, Mauricio Guillermo, and Étienne Miquey

Published in: LIPIcs, Volume 260, 8th International Conference on Formal Structures for Computation and Deduction (FSCD 2023)

Abstract
This work aims at exploring the algebraic structure of concurrent processes and their behavior independently of a particular formalism used to define them. We propose a new algebraic structure called conjunctive involutive monoidal algebra (CIMA) as a basis for an algebraic presentation of concurrent realizability, following ideas of the algebrization program already developed in the realm of classical and intuitionistic realizability. In particular, we show how any CIMA provides a sound interpretation of multiplicative linear logic. This new structure involves, in addition to the tensor and the orthogonal map, a parallel composition. We define a reference model of this structure as induced by a standard process calculus and we use this model to prove that parallel composition cannot be defined from the conjunctive structure alone.
Cite as

Emmanuel Beffara, Félix Castro, Mauricio Guillermo, and Étienne Miquey. Concurrent Realizability on Conjunctive Structures. In 8th International Conference on Formal Structures for Computation and Deduction (FSCD 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 260, pp. 28:1-28:21, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@InProceedings{beffara_et_al:LIPIcs.FSCD.2023.28,
  author =	{Beffara, Emmanuel and Castro, F\'{e}lix and Guillermo, Mauricio and Miquey, \'{E}tienne},
  title =	{{Concurrent Realizability on Conjunctive Structures}},
  booktitle =	{8th International Conference on Formal Structures for Computation and Deduction (FSCD 2023)},
  pages =	{28:1--28:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-277-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{260},
  editor =	{Gaboardi, Marco and van Raamsdonk, Femke},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2023.28},
  URN =		{urn:nbn:de:0030-drops-180124},
  doi =		{10.4230/LIPIcs.FSCD.2023.28},
  annote =	{Keywords: Realizability, Process Algebras, Concurrent Processes, Linear Logic}
}
Document
Artifact
DOI: 10.4230/DARTS.6.2.12
Static Race Detection and Mutex Safety and Liveness for Go Programs (Artifact)

Authors: Julia Gabet and Nobuko Yoshida

Published in: DARTS, Volume 6, Issue 2, Special Issue of the 34th European Conference on Object-Oriented Programming (ECOOP 2020)

Abstract
This artifact contains a version of the Godel tool that checks MiGo+ types - an extension of MiGo from [Lange et al., 2018] including GoL. Given the extracted MiGo+ types, the tool can analyse them using the mCRL2 model checker to check several properties including liveness, safety and data race freedom as defined in our paper. The artifact also includes examples, shipped with both the source of the Godel tool and the benchmark repository. The latter also contains the Go source for the benchmark examples. We provide compiled binaries of the artifact in a Docker image, with instructions on how to use them. Finally, for convenience, the Docker image also contains a binary version of the migoinfer+ tool, developed as a fork from the original migoinfer by Nicholas Ng in [Lange et al., 2018]. This new version adds the ability to extract shared memory pointers as well as Mutex and RWMutex locks.
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Julia Gabet and Nobuko Yoshida. Static Race Detection and Mutex Safety and Liveness for Go Programs (Artifact). In Special Issue of the 34th European Conference on Object-Oriented Programming (ECOOP 2020). Dagstuhl Artifacts Series (DARTS), Volume 6, Issue 2, pp. 12:1-12:3, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)

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@Article{gabet_et_al:DARTS.6.2.12,
  author =	{Gabet, Julia and Yoshida, Nobuko},
  title =	{{Static Race Detection and Mutex Safety and Liveness for Go Programs (Artifact)}},
  pages =	{12:1--12:3},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2020},
  volume =	{6},
  number =	{2},
  editor =	{Gabet, Julia and Yoshida, Nobuko},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.6.2.12},
  URN =		{urn:nbn:de:0030-drops-132096},
  doi =		{10.4230/DARTS.6.2.12},
  annote =	{Keywords: Go language, behavioural types, race detection, happens-before relation, safety, liveness}
}
Document
Artifact
DOI: 10.4230/DARTS.6.2.18
Multiparty Session Programming with Global Protocol Combinators (Artifact)

Authors: Keigo Imai, Rumyana Neykova, Nobuko Yoshida, and Shoji Yuen

Published in: DARTS, Volume 6, Issue 2, Special Issue of the 34th European Conference on Object-Oriented Programming (ECOOP 2020)

Abstract
In the paper "Multiparty Session Programming with Global Protocol Combinators", we introduce a library, ocaml-mpst for programming with global combinators - a set of functions for writing and verifying multiparty protocols in OCaml. Local behaviours for all processes in a protocol are inferred at once from a global combinator. Our approach enables fully-static verification and implementation of the whole protocol, from the protocol specification to the process implementations, to happen in the same language. This artifact is the source code of ocaml-mpst, with all the examples and benchmarks discussed in the paper.
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Keigo Imai, Rumyana Neykova, Nobuko Yoshida, and Shoji Yuen. Multiparty Session Programming with Global Protocol Combinators (Artifact). In Special Issue of the 34th European Conference on Object-Oriented Programming (ECOOP 2020). Dagstuhl Artifacts Series (DARTS), Volume 6, Issue 2, pp. 18:1-18:2, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)

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@Article{imai_et_al:DARTS.6.2.18,
  author =	{Imai, Keigo and Neykova, Rumyana and Yoshida, Nobuko and Yuen, Shoji},
  title =	{{Multiparty Session Programming with Global Protocol Combinators (Artifact)}},
  pages =	{18:1--18:2},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2020},
  volume =	{6},
  number =	{2},
  editor =	{Imai, Keigo and Neykova, Rumyana and Yoshida, Nobuko and Yuen, Shoji},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.6.2.18},
  URN =		{urn:nbn:de:0030-drops-132159},
  doi =		{10.4230/DARTS.6.2.18},
  annote =	{Keywords: Multiparty Session Types, Communication Protocol, Concurrent and Distributed Programming, OCaml}
}
Document
DOI: 10.4230/LIPIcs.FUN.2021.8
An Optimal Algorithm for Online Freeze-Tag

Authors: Josh Brunner and Julian Wellman

Published in: LIPIcs, Volume 157, 10th International Conference on Fun with Algorithms (FUN 2021) (2020)

Abstract
In the freeze-tag problem, one active robot must wake up many frozen robots. The robots are considered as points in a metric space, where active robots move at a constant rate and activate other robots by visiting them. In the (time-dependent) online variant of the problem, each frozen robot is not revealed until a specified time. Hammar, Nilsson, and Persson have shown that no online algorithm can achieve a competitive ratio better than 7/3 for online freeze-tag, and posed the question of whether an O(1)-competitive algorithm exists. We provide a (1+√2)-competitive algorithm for online time-dependent freeze-tag, and show that this is the best possible: there does not exist an algorithm which achieves a lower competitive ratio on every metric space.
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Josh Brunner and Julian Wellman. An Optimal Algorithm for Online Freeze-Tag. In 10th International Conference on Fun with Algorithms (FUN 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 157, pp. 8:1-8:11, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)

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@InProceedings{brunner_et_al:LIPIcs.FUN.2021.8,
  author =	{Brunner, Josh and Wellman, Julian},
  title =	{{An Optimal Algorithm for Online Freeze-Tag}},
  booktitle =	{10th International Conference on Fun with Algorithms (FUN 2021)},
  pages =	{8:1--8:11},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-145-0},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{157},
  editor =	{Farach-Colton, Martin and Prencipe, Giuseppe and Uehara, Ryuhei},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FUN.2021.8},
  URN =		{urn:nbn:de:0030-drops-127693},
  doi =		{10.4230/LIPIcs.FUN.2021.8},
  annote =	{Keywords: Online algorithm, competitive ratio, freeze-tag}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.TIME.2020.2
Temporal Modalities in Answer Set Programming (Invited Talk)

Authors: Pedro Cabalar

Published in: LIPIcs, Volume 178, 27th International Symposium on Temporal Representation and Reasoning (TIME 2020)

Abstract
Based on the answer set (or stable model) semantics for logic programs, Answer Set Programming (ASP) has become one of the most successful paradigms for practical Knowledge Representation and problem solving. Although ASP is naturally equipped for solving static combinatorial problems up to NP complexity (or ΣP2 in the disjunctive case) its application to temporal scenarios has been frequent since its very beginning, partly due to its early use for reasoning about actions and change. Temporal problems normally suppose an extra challenge for ASP for several reasons. On the one hand, they normally raise the complexity (in the case of classical planning, for instance, it becomes PSPACE-complete), although this is usually accounted for by making repeated calls to an ASP solver. On the other hand, temporal scenarios also pose a representational challenge, since the basic ASP language does not support temporal expressions. To fill this representational gap, a temporal extension of ASP called Temporal Equilibrium Logic (TEL) was proposed in and extensively studied later. This formalism constitutes a modal, linear-time extension of Equilibrium Logic which, in its turn, is a complete logical characterisation of (standard) ASP based on the intermediate logic of Here-and-There (HT). As a result, TEL is an expressive non-monotonic modal logic that shares the syntax of Linear-Time Temporal Logic (LTL) but interprets temporal formulas under a non-monotonic semantics that properly extends stable models.
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Pedro Cabalar. Temporal Modalities in Answer Set Programming (Invited Talk). In 27th International Symposium on Temporal Representation and Reasoning (TIME 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 178, pp. 2:1-2:5, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)

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@InProceedings{cabalar:LIPIcs.TIME.2020.2,
  author =	{Cabalar, Pedro},
  title =	{{Temporal Modalities in Answer Set Programming}},
  booktitle =	{27th International Symposium on Temporal Representation and Reasoning (TIME 2020)},
  pages =	{2:1--2:5},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-167-2},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{178},
  editor =	{Mu\~{n}oz-Velasco, Emilio and Ozaki, Ana and Theobald, Martin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2020.2},
  URN =		{urn:nbn:de:0030-drops-129707},
  doi =		{10.4230/LIPIcs.TIME.2020.2},
  annote =	{Keywords: Logic Programming, Temporal Logic, Answer Set Programming, Modal Logic}
}
Document
APPROX
DOI: 10.4230/LIPIcs.APPROX/RANDOM.2020.64
Weighted Maximum Independent Set of Geometric Objects in Turnstile Streams

Authors: Ainesh Bakshi, Nadiia Chepurko, and David P. Woodruff

Published in: LIPIcs, Volume 176, Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2020)

Abstract
We study the Maximum Independent Set problem for geometric objects given in the data stream model. A set of geometric objects is said to be independent if the objects are pairwise disjoint. We consider geometric objects in one and two dimensions, i.e., intervals and disks. Let α be the cardinality of the largest independent set. Our goal is to estimate α in a small amount of space, given that the input is received as a one-pass stream. We also consider a generalization of this problem by assigning weights to each object and estimating β, the largest value of a weighted independent set. We initialize the study of this problem in the turnstile streaming model (insertions and deletions) and provide the first algorithms for estimating α and β. For unit-length intervals, we obtain a (2+ε)-approximation to α and β in poly(log(n)/ε) space. We also show a matching lower bound. Combined with the 3/2-approximation for insertion-only streams by Cabello and Perez-Lanterno [Cabello and Pérez-Lantero, 2017], our result implies a separation between the insertion-only and turnstile model. For unit-radius disks, we obtain a (8√3/π)-approximation to α and β in poly(log(n)/ε) space, which is closely related to the hexagonal circle packing constant. Finally, we provide algorithms for estimating α for arbitrary-length intervals under a bounded intersection assumption and study the parameterized space complexity of estimating α and β, where the parameter is the ratio of maximum to minimum interval length.
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Ainesh Bakshi, Nadiia Chepurko, and David P. Woodruff. Weighted Maximum Independent Set of Geometric Objects in Turnstile Streams. In Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 176, pp. 64:1-64:22, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)

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@InProceedings{bakshi_et_al:LIPIcs.APPROX/RANDOM.2020.64,
  author =	{Bakshi, Ainesh and Chepurko, Nadiia and Woodruff, David P.},
  title =	{{Weighted Maximum Independent Set of Geometric Objects in Turnstile Streams}},
  booktitle =	{Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2020)},
  pages =	{64:1--64:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-164-1},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{176},
  editor =	{Byrka, Jaros{\l}aw and Meka, Raghu},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX/RANDOM.2020.64},
  URN =		{urn:nbn:de:0030-drops-126679},
  doi =		{10.4230/LIPIcs.APPROX/RANDOM.2020.64},
  annote =	{Keywords: Weighted Maximum Independent Set, Geometric Graphs, Turnstile Streams}
}
Document
DOI: 10.4230/OASIcs.ICPEC.2020.3
An Experience of Game-Based Learning in Web Applications Development Courses

Authors: Míriam Antón-Rodríguez, María Ángeles Pérez-Juárez, Francisco Javier Díaz-Pernas, David González-Ortega, Mario Martínez-Zarzuela, and Javier Manuel Aguiar-Pérez

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

Abstract
Preparing graduates for working in the software engineering industry is challenging and requires effective learning frameworks and methodologies. More specifically, the challenge of teaching programming languages and paradigms is a very complex task that needs innovative educational tools. This paper presents a game-based educational tool named eLiza, developed and used to support the teaching and learning of programming languages and paradigms related to the development of web applications. eLiza was initially developed as a Moodle-based web application because Moodle is the educational eLearning platform used at the University of Valladolid, but as the use of mobile devices is constantly increasing, Android and iOS versions were created later in order to facilitate the access of the students to the games. This paper describes the main elements and the mechanics in playing eLiza. And it also describes an experience of its use in two engineering courses related to web programming applications development, offered to students in two different engineering study programs at the University of Valladolid, during the academic years 2017-2018 and 2018-2019. The great majority of the students, more than 75%, considered that the use of the eLiza game-based educational tool was positive to improve the teaching and learning process of the topics covered by the courses.
Cite as

Míriam Antón-Rodríguez, María Ángeles Pérez-Juárez, Francisco Javier Díaz-Pernas, David González-Ortega, Mario Martínez-Zarzuela, and Javier Manuel Aguiar-Pérez. An Experience of Game-Based Learning in Web Applications Development Courses. In First International Computer Programming Education Conference (ICPEC 2020). Open Access Series in Informatics (OASIcs), Volume 81, pp. 3:1-3:11, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)

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@InProceedings{antonrodriguez_et_al:OASIcs.ICPEC.2020.3,
  author =	{Ant\'{o}n-Rodr{\'\i}guez, M{\'\i}riam and P\'{e}rez-Ju\'{a}rez, Mar{\'\i}a \'{A}ngeles and D{\'\i}az-Pernas, Francisco Javier and Gonz\'{a}lez-Ortega, David and Mart{\'\i}nez-Zarzuela, Mario and Aguiar-P\'{e}rez, Javier Manuel},
  title =	{{An Experience of Game-Based Learning in Web Applications Development Courses}},
  booktitle =	{First International Computer Programming Education Conference (ICPEC 2020)},
  pages =	{3:1--3:11},
  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.2020.3},
  URN =		{urn:nbn:de:0030-drops-122901},
  doi =		{10.4230/OASIcs.ICPEC.2020.3},
  annote =	{Keywords: eLearning, mLearning, Game-based Learning, Programming Languages, Web Applications Development}
}
Document
DOI: 10.4230/LITES-v006-i001-a003
A Survey of Probabilistic Timing Analysis Techniques for Real-Time Systems

Authors: Robert I. Davis and Liliana Cucu-Grosjean

Published in: LITES, Volume 6, Issue 1 (2019). Leibniz Transactions on Embedded Systems, Volume 6, Issue 1

Abstract
This survey covers probabilistic timing analysis techniques for real-time systems. It reviews and critiques the key results in the field from its origins in 2000 to the latest research published up to the end of August 2018. The survey provides a taxonomy of the different methods used, and a classification of existing research. A detailed review is provided covering the main subject areas: static probabilistic timing analysis, measurement-based probabilistic timing analysis, and hybrid methods. In addition, research on supporting mechanisms and techniques, case studies, and evaluations is also reviewed. The survey concludes by identifying open issues, key challenges and possible directions for future research.
Cite as

Robert I. Davis and Liliana Cucu-Grosjean. A Survey of Probabilistic Timing Analysis Techniques for Real-Time Systems. In LITES, Volume 6, Issue 1 (2019). Leibniz Transactions on Embedded Systems, Volume 6, Issue 1, pp. 03:1-03:60, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2019)

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@Article{davis_et_al:LITES-v006-i001-a003,
  author =	{Davis, Robert I. and Cucu-Grosjean, Liliana},
  title =	{{A Survey of Probabilistic Timing Analysis Techniques for Real-Time Systems}},
  booktitle =	{LITES, Volume 6, Issue 1 (2019)},
  pages =	{03:1--03:60},
  journal =	{Leibniz Transactions on Embedded Systems},
  ISSN =	{2199-2002},
  year =	{2019},
  volume =	{6},
  number =	{1},
  editor =	{Davis, Robert I. and Cucu-Grosjean, Liliana},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v006-i001-a003},
  doi =		{10.4230/LITES-v006-i001-a003},
  annote =	{Keywords: Probabilistic, real-time, timing analysis}
}
Document
DOI: 10.4230/LIPIcs.CONCUR.2015.114
Reactive Synthesis Without Regret

Authors: Paul Hunter, Guillermo A. Pérez, and Jean-François Raskin

Published in: LIPIcs, Volume 42, 26th International Conference on Concurrency Theory (CONCUR 2015)

Abstract
Two-player zero-sum games of infinite duration and their quantitative versions are used in verification to model the interaction between a controller (Eve) and its environment (Adam). The question usually addressed is that of the existence (and computability) of a strategy for Eve that can maximize her payoff against any strategy of Adam. In this work, we are interested in strategies of Eve that minimize her regret, i.e. strategies that minimize the difference between her actual payoff and the payoff she could have achieved if she had known the strategy of Adam in advance. We give algorithms to compute the strategies of Eve that ensure minimal regret against an adversary whose choice of strategy is (i) unrestricted, (ii) limited to positional strategies, or (iii) limited to word strategies, and show that the two last cases have natural modelling applications. We also show that our notion of regret minimization in which Adam is limited to word strategies generalizes the notion of good for games introduced by Henzinger and Piterman, and is related to the notion of determinization by pruning due to Aminof, Kupferman and Lampert.
Cite as

Paul Hunter, Guillermo A. Pérez, and Jean-François Raskin. Reactive Synthesis Without Regret. In 26th International Conference on Concurrency Theory (CONCUR 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 42, pp. 114-127, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2015)

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@InProceedings{hunter_et_al:LIPIcs.CONCUR.2015.114,
  author =	{Hunter, Paul and P\'{e}rez, Guillermo A. and Raskin, Jean-Fran\c{c}ois},
  title =	{{Reactive Synthesis Without Regret}},
  booktitle =	{26th International Conference on Concurrency Theory (CONCUR 2015)},
  pages =	{114--127},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-91-0},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{42},
  editor =	{Aceto, Luca and de Frutos Escrig, David},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2015.114},
  URN =		{urn:nbn:de:0030-drops-53675},
  doi =		{10.4230/LIPIcs.CONCUR.2015.114},
  annote =	{Keywords: Quantitative games, regret, verification, synthesis, game theory}
}
Document
DOI: 10.4230/LIPIcs.CONCUR.2015.398
Characteristic Bisimulation for Higher-Order Session Processes

Authors: Dimitrios Kouzapas, Jorge A. Pérez, and Nobuko Yoshida

Published in: LIPIcs, Volume 42, 26th International Conference on Concurrency Theory (CONCUR 2015)

Abstract
Characterising contextual equivalence is a long-standing issue for higher-order (process) languages. In the setting of a higher-order pi-calculus with sessions, we develop characteristic bisimilarity, a typed bisimilarity which fully characterises contextual equivalence. To our knowledge, ours is the first characterisation of its kind. Using simple values inhabiting (session) types, our approach distinguishes from untyped methods for characterising contextual equivalence in higher-order processes: we show that observing as inputs only a precise finite set of higher-order values suffices to reason about higher-order session processes. We demonstrate how characteristic bisimilarity can be used to justify optimisations in session protocols with mobile code communication.
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Dimitrios Kouzapas, Jorge A. Pérez, and Nobuko Yoshida. Characteristic Bisimulation for Higher-Order Session Processes. In 26th International Conference on Concurrency Theory (CONCUR 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 42, pp. 398-411, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2015)

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@InProceedings{kouzapas_et_al:LIPIcs.CONCUR.2015.398,
  author =	{Kouzapas, Dimitrios and P\'{e}rez, Jorge A. and Yoshida, Nobuko},
  title =	{{Characteristic Bisimulation for Higher-Order Session Processes}},
  booktitle =	{26th International Conference on Concurrency Theory (CONCUR 2015)},
  pages =	{398--411},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-91-0},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{42},
  editor =	{Aceto, Luca and de Frutos Escrig, David},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2015.398},
  URN =		{urn:nbn:de:0030-drops-53659},
  doi =		{10.4230/LIPIcs.CONCUR.2015.398},
  annote =	{Keywords: Behavioural equivalences, session types, higher-order process calculi}
}
Document
DOI: 10.4230/DagSemProc.08091.9
Learning Grammatical Models for Object Recognition

Authors: Meg Aycinena Lippow, Leslie Pack Kaelbling, and Tomas Lozano-Perez

Published in: Dagstuhl Seminar Proceedings, Volume 8091, Logic and Probability for Scene Interpretation (2008)

Abstract
Many object recognition systems are limited by their inability to share common parts or structure among related object classes. This capability is desirable because it allows information about parts and relationships in one object class to be generalized to other classes for which it is relevant. This ability has the potential to allow effective parameter learning from fewer examples and better generalization of the learned models to unseen instances, and it enables more efficient recognition. With this goal in mind, we have designed a representation and recognition framework that captures structural variability and shared part structure within and among object classes. The framework uses probabilistic geometric grammars (PGGs) to represent object classes recursively in terms of their parts, thereby exploiting the hierarchical and substitutive structure inherent to many types of objects. To incorporate geometric and appearance information, we extend traditional probabilistic context-free grammars to represent distributions over the relative geometric characteristics of object parts as well as the appearance of primitive parts. We describe an efficient dynamic programming algorithm for object categorization and localization in images given a PGG model. We also develop an EM algorithm to estimate the parameters of a grammar structure from training data, and a search-based structure learning approach that finds a compact grammar to explain the image data while sharing substructure among classes. Finally, we describe a set of experiments that demonstrate empirically that the system provides a performance benefit.
Cite as

Meg Aycinena Lippow, Leslie Pack Kaelbling, and Tomas Lozano-Perez. Learning Grammatical Models for Object Recognition. In Logic and Probability for Scene Interpretation. Dagstuhl Seminar Proceedings, Volume 8091, pp. 1-15, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2008)

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@InProceedings{aycinenalippow_et_al:DagSemProc.08091.9,
  author =	{Aycinena Lippow, Meg and Kaelbling, Leslie Pack and Lozano-Perez, Tomas},
  title =	{{Learning Grammatical Models for Object Recognition}},
  booktitle =	{Logic and Probability for Scene Interpretation},
  pages =	{1--15},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2008},
  volume =	{8091},
  editor =	{Anthony G. Cohn and David C. Hogg and Ralf M\"{o}ller and Bernd Neumann},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.08091.9},
  URN =		{urn:nbn:de:0030-drops-16113},
  doi =		{10.4230/DagSemProc.08091.9},
  annote =	{Keywords: Object recognition, grammars, structure learning}
}
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