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Documents authored by Murlak, Filip

Document
DOI: 10.4230/LIPIcs.ICDT.2024.22
Evaluating Graph Queries Using Semantic Treewidth

Authors: Cristina Feier, Tomasz Gogacz, and Filip Murlak

Published in: LIPIcs, Volume 290, 27th International Conference on Database Theory (ICDT 2024)

Abstract
Unions of conjunctive two-way regular path queries (UC2RPQs) are a common abstraction of query languages for graph databases, much like unions of conjunctive queries (UCQs) in the relational case. As in the case of UCQs, their evaluation is NP-complete in combined complexity. Semantic tree-width, i.e. the minimal treewidth of equivalent queries, has been proposed as a candidate criterion to characterize fixed-parameter tractability of UC2RPQs. It was recently shown how to decide the semantic tree-width of a UC2RPQ, by constructing the best under-approximation of a given treewidth, in the form of a UC2RPQ of size doubly exponential in the size of the original query. This leads to an fpt algorithm for evaluating UC2RPQs of semantic TW k which runs in time doubly exponential in the size of the parameter, i.e. in the UC2RPQ. Here we describe a more efficient fpt algorithm for evaluating UC2RPQs of semantic treewidth k which runs in time singly exponential in the size of the parameter. We do this by a careful construction of a witness query which, while still being doubly exponential, can be represented as a Datalog program of bounded width and singly exponential size.
Cite as

Cristina Feier, Tomasz Gogacz, and Filip Murlak. Evaluating Graph Queries Using Semantic Treewidth. In 27th International Conference on Database Theory (ICDT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 290, pp. 22:1-22:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{feier_et_al:LIPIcs.ICDT.2024.22,
  author =	{Feier, Cristina and Gogacz, Tomasz and Murlak, Filip},
  title =	{{Evaluating Graph Queries Using Semantic Treewidth}},
  booktitle =	{27th International Conference on Database Theory (ICDT 2024)},
  pages =	{22:1--22:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-312-6},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{290},
  editor =	{Cormode, Graham and Shekelyan, Michael},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2024.22},
  URN =		{urn:nbn:de:0030-drops-198048},
  doi =		{10.4230/LIPIcs.ICDT.2024.22},
  annote =	{Keywords: conjunctive two-way regular path queries, fixed-parameter tractable evaluation, semantic treewidth, Datalog encoding, optimization}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2023.1
A Researcher’s Digest of GQL (Invited Talk)

Authors: Nadime Francis, Amélie Gheerbrant, Paolo Guagliardo, Leonid Libkin, Victor Marsault, Wim Martens, Filip Murlak, Liat Peterfreund, Alexandra Rogova, and Domagoj Vrgoč

Published in: LIPIcs, Volume 255, 26th International Conference on Database Theory (ICDT 2023)

Abstract
GQL (Graph Query Language) is being developed as a new ISO standard for graph query languages to play the same role for graph databases as SQL plays for relational. In parallel, an extension of SQL for querying property graphs, SQL/PGQ, is added to the SQL standard; it shares the graph pattern matching functionality with GQL. Both standards (not yet published) are hard-to-understand specifications of hundreds of pages. The goal of this paper is to present a digest of the language that is easy for the research community to understand, and thus to initiate research on these future standards for querying graphs. The paper concentrates on pattern matching features shared by GQL and SQL/PGQ, as well as querying facilities of GQL.
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Nadime Francis, Amélie Gheerbrant, Paolo Guagliardo, Leonid Libkin, Victor Marsault, Wim Martens, Filip Murlak, Liat Peterfreund, Alexandra Rogova, and Domagoj Vrgoč. A Researcher’s Digest of GQL (Invited Talk). In 26th International Conference on Database Theory (ICDT 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 255, pp. 1:1-1:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{francis_et_al:LIPIcs.ICDT.2023.1,
  author =	{Francis, Nadime and Gheerbrant, Am\'{e}lie and Guagliardo, Paolo and Libkin, Leonid and Marsault, Victor and Martens, Wim and Murlak, Filip and Peterfreund, Liat and Rogova, Alexandra and Vrgo\v{c}, Domagoj},
  title =	{{A Researcher’s Digest of GQL}},
  booktitle =	{26th International Conference on Database Theory (ICDT 2023)},
  pages =	{1:1--1:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-270-9},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{255},
  editor =	{Geerts, Floris and Vandevoort, Brecht},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2023.1},
  URN =		{urn:nbn:de:0030-drops-177434},
  doi =		{10.4230/LIPIcs.ICDT.2023.1},
  annote =	{Keywords: GQL, Property Graph, Query Language, Graph Database, Pattern matching, Multi-Graph}
}
Document
DOI: 10.4230/DagMan.7.1.1
Research Directions for Principles of Data Management (Dagstuhl Perspectives Workshop 16151)

Authors: Serge Abiteboul, Marcelo Arenas, Pablo Barceló, Meghyn Bienvenu, Diego Calvanese, Claire David, Richard Hull, Eyke Hüllermeier, Benny Kimelfeld, Leonid Libkin, Wim Martens, Tova Milo, Filip Murlak, Frank Neven, Magdalena Ortiz, Thomas Schwentick, Julia Stoyanovich, Jianwen Su, Dan Suciu, Victor Vianu, and Ke Yi

Published in: Dagstuhl Manifestos, Volume 7, Issue 1 (2018)

Abstract
The area of Principles of Data Management (PDM) has made crucial contributions to the development of formal frameworks for understanding and managing data and knowledge. This work has involved a rich cross-fertilization between PDM and other disciplines in mathematics and computer science, including logic, complexity theory, and knowledge representation. We anticipate on-going expansion of PDM research as the technology and applications involving data management continue to grow and evolve. In particular, the lifecycle of Big Data Analytics raises a wealth of challenge areas that PDM can help with. In this report we identify some of the most important research directions where the PDM community has the potential to make significant contributions. This is done from three perspectives: potential practical relevance, results already obtained, and research questions that appear surmountable in the short and medium term.
Cite as

Serge Abiteboul, Marcelo Arenas, Pablo Barceló, Meghyn Bienvenu, Diego Calvanese, Claire David, Richard Hull, Eyke Hüllermeier, Benny Kimelfeld, Leonid Libkin, Wim Martens, Tova Milo, Filip Murlak, Frank Neven, Magdalena Ortiz, Thomas Schwentick, Julia Stoyanovich, Jianwen Su, Dan Suciu, Victor Vianu, and Ke Yi. Research Directions for Principles of Data Management (Dagstuhl Perspectives Workshop 16151). In Dagstuhl Manifestos, Volume 7, Issue 1, pp. 1-29, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@Article{abiteboul_et_al:DagMan.7.1.1,
  author =	{Abiteboul, Serge and Arenas, Marcelo and Barcel\'{o}, Pablo and Bienvenu, Meghyn and Calvanese, Diego and David, Claire and Hull, Richard and H\"{u}llermeier, Eyke and Kimelfeld, Benny and Libkin, Leonid and Martens, Wim and Milo, Tova and Murlak, Filip and Neven, Frank and Ortiz, Magdalena and Schwentick, Thomas and Stoyanovich, Julia and Su, Jianwen and Suciu, Dan and Vianu, Victor and Yi, Ke},
  title =	{{Research Directions for Principles of Data Management (Dagstuhl Perspectives Workshop 16151)}},
  pages =	{1--29},
  journal =	{Dagstuhl Manifestos},
  ISSN =	{2193-2433},
  year =	{2018},
  volume =	{7},
  number =	{1},
  editor =	{Abiteboul, Serge and Arenas, Marcelo and Barcel\'{o}, Pablo and Bienvenu, Meghyn and Calvanese, Diego and David, Claire and Hull, Richard and H\"{u}llermeier, Eyke and Kimelfeld, Benny and Libkin, Leonid and Martens, Wim and Milo, Tova and Murlak, Filip and Neven, Frank and Ortiz, Magdalena and Schwentick, Thomas and Stoyanovich, Julia and Su, Jianwen and Suciu, Dan and Vianu, Victor and Yi, Ke},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagMan.7.1.1},
  URN =		{urn:nbn:de:0030-drops-86772},
  doi =		{10.4230/DagMan.7.1.1},
  annote =	{Keywords: database theory, principles of data management, query languages, efficient query processing, query optimization, heterogeneous data, uncertainty, knowledge-enriched data management, machine learning, workflows, human-related data, ethics}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2016.20
Reasoning About Integrity Constraints for Tree-Structured Data

Authors: Wojciech Czerwinski, Claire David, Filip Murlak, and Pawel Parys

Published in: LIPIcs, Volume 48, 19th International Conference on Database Theory (ICDT 2016)

Abstract
We study a class of integrity constraints for tree-structured data modelled as data trees, whose nodes have a label from a finite alphabet and store a data value from an infinite data domain. The constraints require each tuple of nodes selected by a conjunctive query (using navigational axes and labels) to satisfy a positive combination of equalities and a positive combination of inequalities over the stored data values. Such constraints are instances of the general framework of XML-to-relational constraints proposed recently by Niewerth and Schwentick. They cover some common classes of constraints, including W3C XML Schema key and unique constraints, as well as domain restrictions and denial constraints, but cannot express inclusion constraints, such as reference keys. Our main result is that consistency of such integrity constraints with respect to a given schema (modelled as a tree automaton) is decidable. An easy extension gives decidability for the entailment problem. Equivalently, we show that validity and containment of unions of conjunctive queries using navigational axes, labels, data equalities and inequalities is decidable, as long as none of the conjunctive queries uses both equalities and inequalities; without this restriction, both problems are known to be undecidable. In the context of XML data exchange, our result can be used to establish decidability for a consistency problem for XML schema mappings. All the decision procedures are doubly exponential, with matching lower bounds. The complexity may be lowered to singly exponential, when conjunctive queries are replaced by tree patterns, and the number of data comparisons is bounded.
Cite as

Wojciech Czerwinski, Claire David, Filip Murlak, and Pawel Parys. Reasoning About Integrity Constraints for Tree-Structured Data. In 19th International Conference on Database Theory (ICDT 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 48, pp. 20:1-20:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

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@InProceedings{czerwinski_et_al:LIPIcs.ICDT.2016.20,
  author =	{Czerwinski, Wojciech and David, Claire and Murlak, Filip and Parys, Pawel},
  title =	{{Reasoning About Integrity Constraints for Tree-Structured Data}},
  booktitle =	{19th International Conference on Database Theory (ICDT 2016)},
  pages =	{20:1--20:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-002-6},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{48},
  editor =	{Martens, Wim and Zeume, Thomas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2016.20},
  URN =		{urn:nbn:de:0030-drops-57897},
  doi =		{10.4230/LIPIcs.ICDT.2016.20},
  annote =	{Keywords: data trees, integrity constraints, unions of conjunctive queries, schema mappings, entailment, containment, consistency}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2014.279
Consistency of Injective Tree Patterns

Authors: Claire David, Nadime Francis, and Filip Murlak

Published in: LIPIcs, Volume 29, 34th International Conference on Foundation of Software Technology and Theoretical Computer Science (FSTTCS 2014)

Abstract
Testing if an incomplete description of an XML document is consistent, that is, if it describes a real document conforming to the imposed schema, amounts to deciding if a given tree pattern can be matched injectively into a tree accepted by a fixed automaton. This problem can be solved in polynomial time for patterns that use the child relation and the sibling order, but do not use the descendant relation. For general patterns the problem is in NP, but no lower bound has been known so far. We show that the problem is NP-complete already for patterns using only child and descendant relations. The source of hardness turns out to be the interplay between these relations: for patterns using only descendant we give a polynomial algorithm. We also show that the algorithm can be adapted to patterns using descendant and following-sibling, but combining descendant and next-sibling leads to intractability.
Cite as

Claire David, Nadime Francis, and Filip Murlak. Consistency of Injective Tree Patterns. In 34th International Conference on Foundation of Software Technology and Theoretical Computer Science (FSTTCS 2014). Leibniz International Proceedings in Informatics (LIPIcs), Volume 29, pp. 279-290, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2014)

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@InProceedings{david_et_al:LIPIcs.FSTTCS.2014.279,
  author =	{David, Claire and Francis, Nadime and Murlak, Filip},
  title =	{{Consistency of Injective Tree Patterns}},
  booktitle =	{34th International Conference on Foundation of Software Technology and Theoretical Computer Science (FSTTCS 2014)},
  pages =	{279--290},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-77-4},
  ISSN =	{1868-8969},
  year =	{2014},
  volume =	{29},
  editor =	{Raman, Venkatesh and Suresh, S. P.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2014.279},
  URN =		{urn:nbn:de:0030-drops-48496},
  doi =		{10.4230/LIPIcs.FSTTCS.2014.279},
  annote =	{Keywords: XML, incomplete information, injective tree patterns, consistency}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2011.363
Definable Operations On Weakly Recognizable Sets of Trees

Authors: Jacques Duparc, Alessandro Facchini, and Filip Murlak

Published in: LIPIcs, Volume 13, IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2011)

Abstract
Alternating automata on infinite trees induce operations on languages which do not preserve natural equivalence relations, like having the same Mostowski--Rabin index, the same Borel rank, or being continuously reducible to each other (Wadge equivalence). In order to prevent this, alternation needs to be restricted to the choice of direction in the tree. For weak alternating automata with restricted alternation a small set of computable operations generates all definable operations, which implies that the Wadge degree of a given automaton is computable. The weak index and the Borel rank coincide, and are computable. An equivalent automaton of minimal index can be computed in polynomial time (if the productive states of the automaton are given).
Cite as

Jacques Duparc, Alessandro Facchini, and Filip Murlak. Definable Operations On Weakly Recognizable Sets of Trees. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2011). Leibniz International Proceedings in Informatics (LIPIcs), Volume 13, pp. 363-374, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)

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@InProceedings{duparc_et_al:LIPIcs.FSTTCS.2011.363,
  author =	{Duparc, Jacques and Facchini, Alessandro and Murlak, Filip},
  title =	{{Definable Operations On Weakly Recognizable Sets of Trees}},
  booktitle =	{IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2011)},
  pages =	{363--374},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-34-7},
  ISSN =	{1868-8969},
  year =	{2011},
  volume =	{13},
  editor =	{Chakraborty, Supratik and Kumar, Amit},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2011.363},
  URN =		{urn:nbn:de:0030-drops-33361},
  doi =		{10.4230/LIPIcs.FSTTCS.2011.363},
  annote =	{Keywords: alternating automata, Wadge hierarchy, index hierarchy}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2009.2312
The Wadge Hierarchy of Max-Regular Languages

Authors: Jérémie Cabessa, Jacques Duparc, Alessandro Facchini, and Filip Murlak

Published in: LIPIcs, Volume 4, IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (2009)

Abstract
Recently, Miko{\l}aj Boja{\'n}czyk introduced a class of max-regular languages, an extension of regular languages of infinite words preserving manyof its usual properties. This new class can be seen as a different way of generalising the notion of regularity from finite to infinite words. This paper compares regular and max-regular languages in terms of topological complexity.It is proved that up to Wadge equivalence the classes coincide. Moreover, when restricted to $\mathbf{\Delta}^0_2$-languages, the classes contain virtually the same languages. On the other hand, separating examples of arbitrary complexity exceeding $\mathbf{\Delta}^0_2$ are constructed.
Cite as

Jérémie Cabessa, Jacques Duparc, Alessandro Facchini, and Filip Murlak. The Wadge Hierarchy of Max-Regular Languages. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 4, pp. 121-132, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

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@InProceedings{cabessa_et_al:LIPIcs.FSTTCS.2009.2312,
  author =	{Cabessa, J\'{e}r\'{e}mie and Duparc, Jacques and Facchini, Alessandro and Murlak, Filip},
  title =	{{The Wadge Hierarchy of Max-Regular Languages}},
  booktitle =	{IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
  pages =	{121--132},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-13-2},
  ISSN =	{1868-8969},
  year =	{2009},
  volume =	{4},
  editor =	{Kannan, Ravi and Narayan Kumar, K.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2009.2312},
  URN =		{urn:nbn:de:0030-drops-23122},
  doi =		{10.4230/LIPIcs.FSTTCS.2009.2312},
  annote =	{Keywords: Max-regular languages, Wadge hierarchy, Wagner hierarchy}
}
Document
DOI: 10.4230/LIPIcs.STACS.2008.1318
Weak index versus Borel rank

Authors: Filip Murlak

Published in: LIPIcs, Volume 1, 25th International Symposium on Theoretical Aspects of Computer Science (2008)

Abstract
We investigate weak recognizability of deterministic languages of infinite trees. We prove that for deterministic languages the Borel hierarchy and the weak index hierarchy coincide. Furthermore, we propose a procedure computing for a deterministic automaton an equivalent minimal index weak automaton with a quadratic number of states. The algorithm works within the time of solving the emptiness problem.
Cite as

Filip Murlak. Weak index versus Borel rank. In 25th International Symposium on Theoretical Aspects of Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 1, pp. 573-584, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)

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@InProceedings{murlak:LIPIcs.STACS.2008.1318,
  author =	{Murlak, Filip},
  title =	{{Weak index versus Borel rank}},
  booktitle =	{25th International Symposium on Theoretical Aspects of Computer Science},
  pages =	{573--584},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-06-4},
  ISSN =	{1868-8969},
  year =	{2008},
  volume =	{1},
  editor =	{Albers, Susanne and Weil, Pascal},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2008.1318},
  URN =		{urn:nbn:de:0030-drops-13182},
  doi =		{10.4230/LIPIcs.STACS.2008.1318},
  annote =	{Keywords: Weak index, Borel rank, deterministic tree automata}
}
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