23 Search Results for "Silva, Ana"


Document
Use of Programming Aids in Undergraduate Courses

Authors: Ana Rita Peixoto, André Glória, José Luís Silva, Maria Pinto-Albuquerque, Tomás Brandão, and Luís Nunes

Published in: OASIcs, Volume 122, 5th International Computer Programming Education Conference (ICPEC 2024)


Abstract
The use of external tips and applications to help with programming assignments, by novice programmers, is a double-edged sword, it can help by showing examples of problem-solving strategies, but it can also prevent learning because recognizing a good solution is not the same skill as creating one. A study was conducted during the 2superscript{nd} semester of 23/24 in the course of Object Oriented Programming to help understand the impact of the programming aids in learning. The main questions that drove this study were: Which type(s) of assistance do students use when learning to program? When / where do they use it? Does it affect grades? Results, even though with a relatively small sample, seem to indicate that students who used aids have a perception of improved learning when using advice from Colleagues, Copilot-style tools, and Large Language Models. Results of correlating average grades with the usage of tools suggest that experience in using these tools is key for its successful use, but, contrary to students' perceptions, learning gains are marginal in the end result.

Cite as

Ana Rita Peixoto, André Glória, José Luís Silva, Maria Pinto-Albuquerque, Tomás Brandão, and Luís Nunes. Use of Programming Aids in Undergraduate Courses. In 5th International Computer Programming Education Conference (ICPEC 2024). Open Access Series in Informatics (OASIcs), Volume 122, pp. 20:1-20:9, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{peixoto_et_al:OASIcs.ICPEC.2024.20,
  author =	{Peixoto, Ana Rita and Gl\'{o}ria, Andr\'{e} and Silva, Jos\'{e} Lu{\'\i}s and Pinto-Albuquerque, Maria and Brand\~{a}o, Tom\'{a}s and Nunes, Lu{\'\i}s},
  title =	{{Use of Programming Aids in Undergraduate Courses}},
  booktitle =	{5th International Computer Programming Education Conference (ICPEC 2024)},
  pages =	{20:1--20:9},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-347-8},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{122},
  editor =	{Santos, Andr\'{e} L. and Pinto-Albuquerque, Maria},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ICPEC.2024.20},
  URN =		{urn:nbn:de:0030-drops-209894},
  doi =		{10.4230/OASIcs.ICPEC.2024.20},
  annote =	{Keywords: Teaching Programming, Programming aids}
}
Document
An Operational Semantics in Isabelle/HOL-CSP

Authors: Benoît Ballenghien and Burkhart Wolff

Published in: LIPIcs, Volume 309, 15th International Conference on Interactive Theorem Proving (ITP 2024)


Abstract
The theory of Communicating Sequential Processes going back to Hoare and Roscoe is still today a reference model for concurrency. In the fairly rich literature, several versions of operational semantics have been discussed, which should be consistent with the denotational one. This work is based on Isabelle/HOL-CSP 2.0, a shallow embedding of the failure-divergence model of denotational semantics proposed by Hoare, Roscoe and Brookes in the eighties. In several ways, HOL-CSP is actually an extension of the original setting in the sense that it admits higher-order processes and infinite alphabets. In this paper, we present a construction and formal equivalence proofs between operational CSP semantics and the underlying denotational failure-divergence semantics. The construction is based on a definition of the operational transition operator P ⇝e P’ basically via the After operator and the classical failure-divergence refinement. Several choices are discussed to formally derive the operational semantics leading to subtle differences. The derived operational semantics for symbolic Labelled Transition Systems (LTSs) can be potentially used for certifications of model-checker logs as well as combined proof techniques.

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Benoît Ballenghien and Burkhart Wolff. An Operational Semantics in Isabelle/HOL-CSP. In 15th International Conference on Interactive Theorem Proving (ITP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 309, pp. 7:1-7:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{ballenghien_et_al:LIPIcs.ITP.2024.7,
  author =	{Ballenghien, Beno\^{i}t and Wolff, Burkhart},
  title =	{{An Operational Semantics in Isabelle/HOL-CSP}},
  booktitle =	{15th International Conference on Interactive Theorem Proving (ITP 2024)},
  pages =	{7:1--7:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-337-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{309},
  editor =	{Bertot, Yves and Kutsia, Temur and Norrish, Michael},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2024.7},
  URN =		{urn:nbn:de:0030-drops-207355},
  doi =		{10.4230/LIPIcs.ITP.2024.7},
  annote =	{Keywords: Process-Algebra, Semantics, Concurrency, Computational Models, Theorem Proving, Isabelle/HOL}
}
Document
Effect Semantics for Quantum Process Calculi

Authors: Lorenzo Ceragioli, Fabio Gadducci, Giuseppe Lomurno, and Gabriele Tedeschi

Published in: LIPIcs, Volume 311, 35th International Conference on Concurrency Theory (CONCUR 2024)


Abstract
The development of quantum communication protocols sparked the interest in quantum extensions of process calculi and behavioural equivalences, but defining a bisimilarity that matches the observational properties of a quantum-capable system is a surprisingly difficult task. The two proposals explicitly addressing this issue, qCCS and lqCCS, do not define an algorithmic verification scheme: the bisimilarity of two processes is proven by comparing their behaviour under all input states. We introduce a new semantic model based on effects, i.e. probabilistic predicates on quantum states that represent their observable properties. We define and investigate the properties of effect distributions and effect labelled transition systems (eLTSs), generalizing probability distributions and probabilistic labelled transition systems (pLTSs), respectively. As a proof of concept, we provide an eLTS-based semantics for a minimal quantum process algebra, which we prove sound and complete with respect to the observable probabilistic behaviour of quantum processes. To the best of our knowledge, ours is the first algorithmically verifiable proposal that abides to the properties of quantum theory.

Cite as

Lorenzo Ceragioli, Fabio Gadducci, Giuseppe Lomurno, and Gabriele Tedeschi. Effect Semantics for Quantum Process Calculi. In 35th International Conference on Concurrency Theory (CONCUR 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 311, pp. 16:1-16:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{ceragioli_et_al:LIPIcs.CONCUR.2024.16,
  author =	{Ceragioli, Lorenzo and Gadducci, Fabio and Lomurno, Giuseppe and Tedeschi, Gabriele},
  title =	{{Effect Semantics for Quantum Process Calculi}},
  booktitle =	{35th International Conference on Concurrency Theory (CONCUR 2024)},
  pages =	{16:1--16:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-339-3},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{311},
  editor =	{Majumdar, Rupak and Silva, Alexandra},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2024.16},
  URN =		{urn:nbn:de:0030-drops-207886},
  doi =		{10.4230/LIPIcs.CONCUR.2024.16},
  annote =	{Keywords: Quantum process calculi, probabilistic LTSs, effect LTSs}
}
Document
Behavioural Metrics: Compositionality of the Kantorovich Lifting and an Application to Up-To Techniques

Authors: Keri D'Angelo, Sebastian Gurke, Johanna Maria Kirss, Barbara König, Matina Najafi, Wojciech Różowski, and Paul Wild

Published in: LIPIcs, Volume 311, 35th International Conference on Concurrency Theory (CONCUR 2024)


Abstract
Behavioural distances of transition systems modelled via coalgebras for endofunctors generalize traditional notions of behavioural equivalence to a quantitative setting, in which states are equipped with a measure of how (dis)similar they are. Endowing transition systems with such distances essentially relies on the ability to lift functors describing the one-step behavior of the transition systems to the category of pseudometric spaces. We consider the category theoretic generalization of the Kantorovich lifting from transportation theory to the case of lifting functors to quantale-valued relations, which subsumes equivalences, preorders and (directed) metrics. We use tools from fibred category theory, which allow one to see the Kantorovich lifting as arising from an appropriate fibred adjunction. Our main contributions are compositionality results for the Kantorovich lifting, where we show that that the lifting of a composed functor coincides with the composition of the liftings. In addition, we describe how to lift distributive laws in the case where one of the two functors is polynomial (with finite coproducts). These results are essential ingredients for adapting up-to-techniques to the case of quantale-valued behavioural distances. Up-to techniques are a well-known coinductive technique for efficiently showing lower bounds for behavioural distances. We illustrate the results of our paper in two case studies.

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Keri D'Angelo, Sebastian Gurke, Johanna Maria Kirss, Barbara König, Matina Najafi, Wojciech Różowski, and Paul Wild. Behavioural Metrics: Compositionality of the Kantorovich Lifting and an Application to Up-To Techniques. In 35th International Conference on Concurrency Theory (CONCUR 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 311, pp. 20:1-20:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{dangelo_et_al:LIPIcs.CONCUR.2024.20,
  author =	{D'Angelo, Keri and Gurke, Sebastian and Kirss, Johanna Maria and K\"{o}nig, Barbara and Najafi, Matina and R\'{o}\.{z}owski, Wojciech and Wild, Paul},
  title =	{{Behavioural Metrics: Compositionality of the Kantorovich Lifting and an Application to Up-To Techniques}},
  booktitle =	{35th International Conference on Concurrency Theory (CONCUR 2024)},
  pages =	{20:1--20:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-339-3},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{311},
  editor =	{Majumdar, Rupak and Silva, Alexandra},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2024.20},
  URN =		{urn:nbn:de:0030-drops-207921},
  doi =		{10.4230/LIPIcs.CONCUR.2024.20},
  annote =	{Keywords: behavioural metrics, coalgebra, Galois connections, quantales, Kantorovich lifting, up-to techniques}
}
Document
A PSPACE Algorithm for Almost-Sure Rabin Objectives in Multi-Environment MDPs

Authors: Marnix Suilen, Marck van der Vegt, and Sebastian Junges

Published in: LIPIcs, Volume 311, 35th International Conference on Concurrency Theory (CONCUR 2024)


Abstract
Markov Decision Processes (MDPs) model systems with uncertain transition dynamics. Multiple-environment MDPs (MEMDPs) extend MDPs. They intuitively reflect finite sets of MDPs that share the same state and action spaces but differ in the transition dynamics. The key objective in MEMDPs is to find a single strategy that satisfies a given objective in every associated MDP. The main result of this paper is PSPACE-completeness for almost-sure Rabin objectives in MEMDPs. This result clarifies the complexity landscape for MEMDPs and contrasts with results for the more general class of partially observable MDPs (POMDPs), where almost-sure reachability is already EXP-complete, and almost-sure Rabin objectives are undecidable.

Cite as

Marnix Suilen, Marck van der Vegt, and Sebastian Junges. A PSPACE Algorithm for Almost-Sure Rabin Objectives in Multi-Environment MDPs. In 35th International Conference on Concurrency Theory (CONCUR 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 311, pp. 40:1-40:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{suilen_et_al:LIPIcs.CONCUR.2024.40,
  author =	{Suilen, Marnix and van der Vegt, Marck and Junges, Sebastian},
  title =	{{A PSPACE Algorithm for Almost-Sure Rabin Objectives in Multi-Environment MDPs}},
  booktitle =	{35th International Conference on Concurrency Theory (CONCUR 2024)},
  pages =	{40:1--40:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-339-3},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{311},
  editor =	{Majumdar, Rupak and Silva, Alexandra},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2024.40},
  URN =		{urn:nbn:de:0030-drops-208120},
  doi =		{10.4230/LIPIcs.CONCUR.2024.40},
  annote =	{Keywords: Markov Decision Processes, partial observability, linear-time Objectives}
}
Document
Structure-Guided Local Improvement for Maximum Satisfiability

Authors: André Schidler and Stefan Szeider

Published in: LIPIcs, Volume 307, 30th International Conference on Principles and Practice of Constraint Programming (CP 2024)


Abstract
The enhanced performance of today’s MaxSAT solvers has elevated their appeal for many large-scale applications, notably in software analysis and computer-aided design. Our research delves into refining anytime MaxSAT solving by repeatedly identifying and solving with an exact solver smaller subinstances that are chosen based on the graphical structure of the instance. We investigate various strategies to pinpoint these subinstances. This structure-guided selection of subinstances provides an exact solver with a high potential for improving the current solution. Our exhaustive experimental analyses contrast our methodology as instantiated in our tool MaxSLIM with previous studies and benchmark it against leading-edge MaxSAT solvers.

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André Schidler and Stefan Szeider. Structure-Guided Local Improvement for Maximum Satisfiability. In 30th International Conference on Principles and Practice of Constraint Programming (CP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 307, pp. 26:1-26:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{schidler_et_al:LIPIcs.CP.2024.26,
  author =	{Schidler, Andr\'{e} and Szeider, Stefan},
  title =	{{Structure-Guided Local Improvement for Maximum Satisfiability}},
  booktitle =	{30th International Conference on Principles and Practice of Constraint Programming (CP 2024)},
  pages =	{26:1--26:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-336-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{307},
  editor =	{Shaw, Paul},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2024.26},
  URN =		{urn:nbn:de:0030-drops-207112},
  doi =		{10.4230/LIPIcs.CP.2024.26},
  annote =	{Keywords: maximum satisfiability, large neighborhood search (LNS), SAT-based local improvement (SLIM), incomplete MaxSAT, graphical structure, metaheuristic}
}
Document
Distance to Transitivity: New Parameters for Taming Reachability in Temporal Graphs

Authors: Arnaud Casteigts, Nils Morawietz, and Petra Wolf

Published in: LIPIcs, Volume 306, 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)


Abstract
A temporal graph is a graph whose edges only appear at certain points in time. Reachability in these graphs is defined in terms of paths that traverse the edges in chronological order (temporal paths). This form of reachability is neither symmetric nor transitive, the latter having important consequences on the computational complexity of even basic questions, such as computing temporal connected components. In this paper, we introduce several parameters that capture how far a temporal graph 𝒢 is from being transitive, namely, vertex-deletion distance to transitivity and arc-modification distance to transitivity, both being applied to the reachability graph of 𝒢. We illustrate the impact of these parameters on the temporal connected component problem, obtaining several tractability results in terms of fixed-parameter tractability and polynomial kernels. Significantly, these results are obtained without restrictions of the underlying graph, the snapshots, or the lifetime of the input graph. As such, our results isolate the impact of non-transitivity and confirm the key role that it plays in the hardness of temporal graph problems.

Cite as

Arnaud Casteigts, Nils Morawietz, and Petra Wolf. Distance to Transitivity: New Parameters for Taming Reachability in Temporal Graphs. In 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 306, pp. 36:1-36:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{casteigts_et_al:LIPIcs.MFCS.2024.36,
  author =	{Casteigts, Arnaud and Morawietz, Nils and Wolf, Petra},
  title =	{{Distance to Transitivity: New Parameters for Taming Reachability in Temporal Graphs}},
  booktitle =	{49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)},
  pages =	{36:1--36:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-335-5},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{306},
  editor =	{Kr\'{a}lovi\v{c}, Rastislav and Ku\v{c}era, Anton{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2024.36},
  URN =		{urn:nbn:de:0030-drops-205923},
  doi =		{10.4230/LIPIcs.MFCS.2024.36},
  annote =	{Keywords: Temporal graphs, Parameterized complexity, Reachability, Transitivity}
}
Document
Algorithms and Complexity for Path Covers of Temporal DAGs

Authors: Dibyayan Chakraborty, Antoine Dailly, Florent Foucaud, and Ralf Klasing

Published in: LIPIcs, Volume 306, 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)


Abstract
A path cover of a digraph is a collection of paths collectively containing its vertex set. A path cover with minimum cardinality for a directed acyclic graph can be found in polynomial time [Fulkerson, AMS'56; Cáceres et al., SODA'22]. Moreover, Dilworth’s celebrated theorem on chain coverings of partially ordered sets equivalently states that the minimum size of a path cover of a DAG is equal to the maximum size of a set of mutually unreachable vertices. In this paper, we examine how far these classic results can be extended to a dynamic setting. A temporal digraph has an arc set that changes over discrete time-steps; if the underlying digraph is acyclic, then it is a temporal DAG. A temporal path is a directed path in the underlying digraph, such that the time-steps of arcs are strictly increasing along the path. Two temporal paths are temporally disjoint if they do not occupy any vertex at the same time. A temporal path cover is a collection 𝒞 of temporal paths that covers all vertices, and 𝒞 is temporally disjoint if all its temporal paths are pairwise temporally disjoint. We study the computational complexities of the problems of finding a minimum-size temporal (disjoint) path cover (denoted as Temporal Path Cover and Temporally Disjoint Path Cover). On the negative side, we show that both Temporal Path Cover and Temporally Disjoint Path Cover are NP-hard even when the underlying DAG is planar, bipartite, subcubic, and there are only two arc-disjoint time-steps. Moreover, Temporally Disjoint Path Cover remains NP-hard even on temporal oriented trees. We also observe that natural temporal analogues of Dilworth’s theorem on these classes of temporal DAGs do not hold. In contrast, we show that Temporal Path Cover is polynomial-time solvable on temporal oriented trees by a reduction to Clique Cover for (static undirected) weakly chordal graphs (a subclass of perfect graphs for which Clique Cover admits an efficient algorithm). This highlights an interesting algorithmic difference between the two problems. Although it is NP-hard on temporal oriented trees, Temporally Disjoint Path Cover becomes polynomial-time solvable on temporal oriented lines and temporal rooted directed trees. Motivated by the hardness result on trees, we show that, in contrast, Temporal Path Cover admits an XP time algorithm with respect to parameter t_max + tw, where t_max is the maximum time-step and tw is the treewidth of the underlying static undirected graph; moreover, Temporally Disjoint Path Cover admits an FPT algorithm with respect to the same parameterization.

Cite as

Dibyayan Chakraborty, Antoine Dailly, Florent Foucaud, and Ralf Klasing. Algorithms and Complexity for Path Covers of Temporal DAGs. In 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 306, pp. 38:1-38:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{chakraborty_et_al:LIPIcs.MFCS.2024.38,
  author =	{Chakraborty, Dibyayan and Dailly, Antoine and Foucaud, Florent and Klasing, Ralf},
  title =	{{Algorithms and Complexity for Path Covers of Temporal DAGs}},
  booktitle =	{49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)},
  pages =	{38:1--38:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-335-5},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{306},
  editor =	{Kr\'{a}lovi\v{c}, Rastislav and Ku\v{c}era, Anton{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2024.38},
  URN =		{urn:nbn:de:0030-drops-205940},
  doi =		{10.4230/LIPIcs.MFCS.2024.38},
  annote =	{Keywords: Temporal Graphs, Dilworth’s Theorem, DAGs, Path Cover, Temporally Disjoint Paths, Algorithms, Oriented Trees, Treewidth}
}
Document
C_{2k+1}-Coloring of Bounded-Diameter Graphs

Authors: Marta Piecyk

Published in: LIPIcs, Volume 306, 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)


Abstract
For a fixed graph H, in the graph homomorphism problem, denoted by Hom(H), we are given a graph G and we have to determine whether there exists an edge-preserving mapping φ: V(G) → V(H). Note that Hom(C₃), where C₃ is the cycle of length 3, is equivalent to 3-Coloring. The question of whether 3-Coloring is polynomial-time solvable on diameter-2 graphs is a well-known open problem. In this paper we study the Hom(C_{2k+1}) problem on bounded-diameter graphs for k ≥ 2, so we consider all other odd cycles than C₃. We prove that for k ≥ 2, the Hom(C_{2k+1}) problem is polynomial-time solvable on diameter-(k+1) graphs - note that such a result for k = 1 would be precisely a polynomial-time algorithm for 3-Coloring of diameter-2 graphs. Furthermore, we give subexponential-time algorithms for diameter-(k+2) and -(k+3) graphs. We complement these results with a lower bound for diameter-(2k+2) graphs - in this class of graphs the Hom(C_{2k+1}) problem is NP-hard and cannot be solved in subexponential-time, unless the ETH fails. Finally, we consider another direction of generalizing 3-Coloring on diameter-2 graphs. We consider other target graphs H than odd cycles but we restrict ourselves to diameter 2. We show that if H is triangle-free, then Hom(H) is polynomial-time solvable on diameter-2 graphs.

Cite as

Marta Piecyk. C_{2k+1}-Coloring of Bounded-Diameter Graphs. In 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 306, pp. 78:1-78:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{piecyk:LIPIcs.MFCS.2024.78,
  author =	{Piecyk, Marta},
  title =	{{C\underline\{2k+1\}-Coloring of Bounded-Diameter Graphs}},
  booktitle =	{49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)},
  pages =	{78:1--78:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-335-5},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{306},
  editor =	{Kr\'{a}lovi\v{c}, Rastislav and Ku\v{c}era, Anton{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2024.78},
  URN =		{urn:nbn:de:0030-drops-206348},
  doi =		{10.4230/LIPIcs.MFCS.2024.78},
  annote =	{Keywords: graph homomorphism, odd cycles, diameter}
}
Document
A Categorical Approach to DIBI Models

Authors: Tao Gu, Jialu Bao, Justin Hsu, Alexandra Silva, and Fabio Zanasi

Published in: LIPIcs, Volume 299, 9th International Conference on Formal Structures for Computation and Deduction (FSCD 2024)


Abstract
The logic of Dependence and Independence Bunched Implications (DIBI) is a logic to reason about conditional independence (CI); for instance, DIBI formulas can characterise CI in discrete probability distributions and in relational databases, using a probabilistic DIBI model and a similarly-constructed relational model. Despite the similarity of the two models, there lacks a uniform account. As a result, the laborious case-by-case verification of the frame conditions required for constructing new models hinders them from generalising the results to CI in other useful models such that continuous distribution. In this paper, we develop an abstract framework for systematically constructing DIBI models, using category theory as the unifying mathematical language. We show that DIBI models arise from arbitrary symmetric monoidal categories with copy-discard structure. In particular, we use string diagrams - a graphical presentation of monoidal categories - to give a uniform definition of the parallel composition and subkernel relation in DIBI models. Our approach not only generalises known models, but also yields new models of interest and reduces properties of DIBI models to structures in the underlying categories. Furthermore, our categorical framework enables a comparison between string diagrammatic approaches to CI in the literature and a logical notion of CI, defined in terms of the satisfaction of specific DIBI formulas. We show that the logical notion is an extension of string diagrammatic CI under reasonable conditions.

Cite as

Tao Gu, Jialu Bao, Justin Hsu, Alexandra Silva, and Fabio Zanasi. A Categorical Approach to DIBI Models. In 9th International Conference on Formal Structures for Computation and Deduction (FSCD 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 299, pp. 17:1-17:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{gu_et_al:LIPIcs.FSCD.2024.17,
  author =	{Gu, Tao and Bao, Jialu and Hsu, Justin and Silva, Alexandra and Zanasi, Fabio},
  title =	{{A Categorical Approach to DIBI Models}},
  booktitle =	{9th International Conference on Formal Structures for Computation and Deduction (FSCD 2024)},
  pages =	{17:1--17:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-323-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{299},
  editor =	{Rehof, Jakob},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2024.17},
  URN =		{urn:nbn:de:0030-drops-203469},
  doi =		{10.4230/LIPIcs.FSCD.2024.17},
  annote =	{Keywords: Conditional Independence, Dependence Independence Bunched Implications, String Diagrams, Markov Categories}
}
Document
Track A: Algorithms, Complexity and Games
Exploiting Automorphisms of Temporal Graphs for Fast Exploration and Rendezvous

Authors: Konstantinos Dogeas, Thomas Erlebach, Frank Kammer, Johannes Meintrup, and William K. Moses Jr.

Published in: LIPIcs, Volume 297, 51st International Colloquium on Automata, Languages, and Programming (ICALP 2024)


Abstract
Temporal graphs are dynamic graphs where the edge set can change in each time step, while the vertex set stays the same. Exploration of temporal graphs whose snapshot in each time step is a connected graph, called connected temporal graphs, has been widely studied. In this paper, we extend the concept of graph automorphisms from static graphs to temporal graphs and show for the first time that symmetries enable faster exploration: We prove that a connected temporal graph with n vertices and orbit number r (i.e., r is the number of automorphism orbits) can be explored in O(r n^{1+ε}) time steps, for any fixed ε > 0. For r = O(n^c) for constant c < 1, this is a significant improvement over the known tight worst-case bound of Θ(n²) time steps for arbitrary connected temporal graphs. We also give two lower bounds for temporal exploration, showing that Ω(n log n) time steps are required for some inputs with r = O(1) and that Ω(rn) time steps are required for some inputs for any r with 1 ≤ r ≤ n. Moreover, we show that the techniques we develop for fast exploration can be used to derive the following result for rendezvous: Two agents with different programs and without communication ability are placed by an adversary at arbitrary vertices and given full information about the connected temporal graph, except that they do not have consistent vertex labels. Then the two agents can meet at a common vertex after O(n^{1+ε}) time steps, for any constant ε > 0. For some connected temporal graphs with the orbit number being a constant, we also present a complementary lower bound of Ω(nlog n) time steps.

Cite as

Konstantinos Dogeas, Thomas Erlebach, Frank Kammer, Johannes Meintrup, and William K. Moses Jr.. Exploiting Automorphisms of Temporal Graphs for Fast Exploration and Rendezvous. In 51st International Colloquium on Automata, Languages, and Programming (ICALP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 297, pp. 55:1-55:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{dogeas_et_al:LIPIcs.ICALP.2024.55,
  author =	{Dogeas, Konstantinos and Erlebach, Thomas and Kammer, Frank and Meintrup, Johannes and Moses Jr., William K.},
  title =	{{Exploiting Automorphisms of Temporal Graphs for Fast Exploration and Rendezvous}},
  booktitle =	{51st International Colloquium on Automata, Languages, and Programming (ICALP 2024)},
  pages =	{55:1--55:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-322-5},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{297},
  editor =	{Bringmann, Karl and Grohe, Martin and Puppis, Gabriele and Svensson, Ola},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2024.55},
  URN =		{urn:nbn:de:0030-drops-201989},
  doi =		{10.4230/LIPIcs.ICALP.2024.55},
  annote =	{Keywords: dynamic graphs, parameterized algorithms, algorithmic graph theory, graph automorphism, orbit number}
}
Document
Survey
Logics for Conceptual Data Modelling: A Review

Authors: Pablo R. Fillottrani and C. Maria Keet

Published in: TGDK, Volume 2, Issue 1 (2024): Special Issue on Trends in Graph Data and Knowledge - Part 2. Transactions on Graph Data and Knowledge, Volume 2, Issue 1


Abstract
Information modelling for databases and object-oriented information systems avails of conceptual data modelling languages such as EER and UML Class Diagrams. Many attempts exist to add logical rigour to them, for various reasons and with disparate strengths. In this paper we aim to provide a structured overview of the many efforts. We focus on aims, approaches to the formalisation, including key dimensions of choice points, popular logics used, and the main relevant reasoning services. We close with current challenges and research directions.

Cite as

Pablo R. Fillottrani and C. Maria Keet. Logics for Conceptual Data Modelling: A Review. In Special Issue on Trends in Graph Data and Knowledge - Part 2. Transactions on Graph Data and Knowledge (TGDK), Volume 2, Issue 1, pp. 4:1-4:30, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@Article{fillottrani_et_al:TGDK.2.1.4,
  author =	{Fillottrani, Pablo R. and Keet, C. Maria},
  title =	{{Logics for Conceptual Data Modelling: A Review}},
  journal =	{Transactions on Graph Data and Knowledge},
  pages =	{4:1--4:30},
  ISSN =	{2942-7517},
  year =	{2024},
  volume =	{2},
  number =	{1},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/TGDK.2.1.4},
  URN =		{urn:nbn:de:0030-drops-198616},
  doi =		{10.4230/TGDK.2.1.4},
  annote =	{Keywords: Conceptual Data Modelling, EER, UML, Description Logics, OWL}
}
Document
Snapshot Disjointness in Temporal Graphs

Authors: Allen Ibiapina and Ana Silva

Published in: LIPIcs, Volume 257, 2nd Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2023)


Abstract
In the study of temporal graphs, only paths respecting the flow of time are relevant. In this context, many concepts of walks disjointness have been proposed over the years, and the validity of Menger’s Theorem, as well as the complexity of related problems, has been investigated. Menger’s Theorem states that the maximum number of disjoint paths between two vertices is equal to the minimum number of vertices required to disconnect them. In this paper, we introduce and investigate a type of disjointness that is only time dependent. Two walks are said to be snapshot disjoint if they are not active in a same snapshot (also called timestep). The related paths and cut problems are then defined and proved to be W[1]-hard and XP-time solvable when parameterized by the size of the solution. Additionally, in the light of the definition of Mengerian graphs given by Kempe, Kleinberg and Kumar in their seminal paper (STOC'2000), we define a Mengerian graph for time as a graph G for which there is no time labeling for its edges where Menger’s Theorem does not hold in the context of snapshot disjointness. We then give a characterization of Mengerian graphs in terms of forbidden structures and provide a polynomial-time recognition algorithm. Finally, we also prove that, given a temporal graph (G,λ) and a pair of vertices s,z ∈ V(G), deciding whether at most h multiedges can separate s from z is NP-complete, where one multiedge uv is the set of all edges with endpoints u and v.

Cite as

Allen Ibiapina and Ana Silva. Snapshot Disjointness in Temporal Graphs. In 2nd Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 257, pp. 1:1-1:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{ibiapina_et_al:LIPIcs.SAND.2023.1,
  author =	{Ibiapina, Allen and Silva, Ana},
  title =	{{Snapshot Disjointness in Temporal Graphs}},
  booktitle =	{2nd Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2023)},
  pages =	{1:1--1:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-275-4},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{257},
  editor =	{Doty, David and Spirakis, Paul},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAND.2023.1},
  URN =		{urn:nbn:de:0030-drops-179379},
  doi =		{10.4230/LIPIcs.SAND.2023.1},
  annote =	{Keywords: Temporal graphs, Menger’s Theorem, Snapshot disjointness}
}
Document
Introductory Programming in Higher Education: A Systematic Literature Review

Authors: Gabryella Rodrigues, Ana Francisca Monteiro, and António Osório

Published in: OASIcs, Volume 102, Third International Computer Programming Education Conference (ICPEC 2022)


Abstract
A systematic literature review was performed on 33 papers obtained from the ACM, IEEE and Sciencedirect databases, in order to understand in depth, the introductory programming discipline (CS1) in higher education. Recently published works have been covered, providing an overview of the teaching-learning process of introductory programming and enabling to find out whether the research developed by universities worldwide is in line with the proposals made by ACM/IEEE-CS group for computer courses, regarding the transition to the competency-based model. The results show that the new techniques/technologies currently used in software development, as an example of agile methodology, has influenced the teaching-learning process of CS1 together with methods such as visual programming and e-learning. The analyzed papers discuss the importance of developing not only technical, but also social skills, corroborating that methodologies used in introductory programming courses need to focus on preparing students for an increasingly competitive market, associating new skills with technical aspects.

Cite as

Gabryella Rodrigues, Ana Francisca Monteiro, and António Osório. Introductory Programming in Higher Education: A Systematic Literature Review. In Third International Computer Programming Education Conference (ICPEC 2022). Open Access Series in Informatics (OASIcs), Volume 102, pp. 4:1-4:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{rodrigues_et_al:OASIcs.ICPEC.2022.4,
  author =	{Rodrigues, Gabryella and Monteiro, Ana Francisca and Os\'{o}rio, Ant\'{o}nio},
  title =	{{Introductory Programming in Higher Education: A Systematic Literature Review}},
  booktitle =	{Third International Computer Programming Education Conference (ICPEC 2022)},
  pages =	{4:1--4:17},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-229-7},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{102},
  editor =	{Sim\~{o}es, Alberto and Silva, Jo\~{a}o Carlos},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ICPEC.2022.4},
  URN =		{urn:nbn:de:0030-drops-166085},
  doi =		{10.4230/OASIcs.ICPEC.2022.4},
  annote =	{Keywords: systematic literature review, CS1, introductory programming, teaching programming, learning programming}
}
Document
Feedback Systems for Students Solving Problems Related to Polynomials of Degree Two or Lower

Authors: Luke Adrian Gubbins Bayzid, Ana Maria Reis D'Azevedo Breda, Eugénio Alexandre Miguel Rocha, and José Manuel Dos Santos Dos Santos

Published in: OASIcs, Volume 102, Third International Computer Programming Education Conference (ICPEC 2022)


Abstract
In this paper, we present the first attempts to design and implement an algorithm that effectively responds to errors in a student’s resolution in problems related to polynomials of degree two or lower. The algorithm analyzes the student’s input by comparing pre-established resolution patterns. The obtained results of the implementation show that the algorithm is effective at the classes of problems created within the project’s scope. Future work will concern the expansion of the number of classes to other common types of problems, such as higher-degree polynomials, and its use at a large scale using open-source software with CAS capabilities.

Cite as

Luke Adrian Gubbins Bayzid, Ana Maria Reis D'Azevedo Breda, Eugénio Alexandre Miguel Rocha, and José Manuel Dos Santos Dos Santos. Feedback Systems for Students Solving Problems Related to Polynomials of Degree Two or Lower. In Third International Computer Programming Education Conference (ICPEC 2022). Open Access Series in Informatics (OASIcs), Volume 102, pp. 5:1-5:10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{bayzid_et_al:OASIcs.ICPEC.2022.5,
  author =	{Bayzid, Luke Adrian Gubbins and Breda, Ana Maria Reis D'Azevedo and Rocha, Eug\'{e}nio Alexandre Miguel and Dos Santos, Jos\'{e} Manuel Dos Santos},
  title =	{{Feedback Systems for Students Solving Problems Related to Polynomials of Degree Two or Lower}},
  booktitle =	{Third International Computer Programming Education Conference (ICPEC 2022)},
  pages =	{5:1--5:10},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-229-7},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{102},
  editor =	{Sim\~{o}es, Alberto and Silva, Jo\~{a}o Carlos},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ICPEC.2022.5},
  URN =		{urn:nbn:de:0030-drops-166094},
  doi =		{10.4230/OASIcs.ICPEC.2022.5},
  annote =	{Keywords: Automatic feedback, Algorithms, Algebraic systems}
}
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