36 Search Results for "Benedikt, Michael"

Volume

LIPIcs, Volume 68

20th International Conference on Database Theory (ICDT 2017)

ICDT 2017, March 21-24, 2017, Venice, Italy

Editors: Michael Benedikt and Giorgio Orsi

Document
Track B: Automata, Logic, Semantics, and Theory of Programming
DOI: 10.4230/LIPIcs.ICALP.2023.112
The Complexity of Presburger Arithmetic with Power or Powers

Authors: Michael Benedikt, Dmitry Chistikov, and Alessio Mansutti

Published in: LIPIcs, Volume 261, 50th International Colloquium on Automata, Languages, and Programming (ICALP 2023)

Abstract
We investigate expansions of Presburger arithmetic (Pa), i.e., the theory of the integers with addition and order, with additional structure related to exponentiation: either a function that takes a number to the power of 2, or a predicate 2^ℕ for the powers of 2. The latter theory, denoted Pa(2^ℕ(·)), was introduced by Büchi as a first attempt at characterizing the sets of tuples of numbers that can be expressed using finite automata; Büchi’s method does not give an elementary upper bound, and the complexity of this theory has been open. The former theory, denoted as Pa(λx.2^|x|), was shown decidable by Semenov; while the decision procedure for this theory differs radically from the automata-based method proposed by Büchi, Semenov’s method is also non-elementary. And in fact, the theory with the power function has a non-elementary lower bound. In this paper, we show that while Semenov’s and Büchi’s approaches yield non-elementary blow-ups for Pa(2^ℕ(·)), the theory is in fact decidable in triply exponential time, similarly to the best known quantifier-elimination algorithm for Pa. We also provide a NExpTime upper bound for the existential fragment of Pa(λx.2^|x|), a step towards a finer-grained analysis of its complexity. Both these results are established by analyzing a single parameterized satisfiability algorithm for Pa(λx.2^|x|), which can be specialized to either the setting of Pa(2^ℕ(·)) or the existential theory of Pa(λx.2^|x|). Besides the new upper bounds for the existential theory of Pa(λx.2^|x|) and Pa(2^ℕ(·)), we believe our algorithm provides new intuition for the decidability of these theories, and for the features that lead to non-elementary blow-ups.
Cite as

Michael Benedikt, Dmitry Chistikov, and Alessio Mansutti. The Complexity of Presburger Arithmetic with Power or Powers. In 50th International Colloquium on Automata, Languages, and Programming (ICALP 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 261, pp. 112:1-112:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{benedikt_et_al:LIPIcs.ICALP.2023.112,
  author =	{Benedikt, Michael and Chistikov, Dmitry and Mansutti, Alessio},
  title =	{{The Complexity of Presburger Arithmetic with Power or Powers}},
  booktitle =	{50th International Colloquium on Automata, Languages, and Programming (ICALP 2023)},
  pages =	{112:1--112:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-278-5},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{261},
  editor =	{Etessami, Kousha and Feige, Uriel and Puppis, Gabriele},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2023.112},
  URN =		{urn:nbn:de:0030-drops-181641},
  doi =		{10.4230/LIPIcs.ICALP.2023.112},
  annote =	{Keywords: arithmetic theories, exponentiation, decision procedures}
}
Document
DOI: 10.4230/LIPIcs.SoCG.2022.14
Quasi-Universality of Reeb Graph Distances

Authors: Ulrich Bauer, Håvard Bakke Bjerkevik, and Benedikt Fluhr

Published in: LIPIcs, Volume 224, 38th International Symposium on Computational Geometry (SoCG 2022)

Abstract
We establish bi-Lipschitz bounds certifying quasi-universality (universality up to a constant factor) for various distances between Reeb graphs: the interleaving distance, the functional distortion distance, and the functional contortion distance. The definition of the latter distance is a novel contribution, and for the special case of contour trees we also prove strict universality of this distance. Furthermore, we prove that for the special case of merge trees the functional contortion distance coincides with the interleaving distance, yielding universality of all four distances in this case.
Cite as

Ulrich Bauer, Håvard Bakke Bjerkevik, and Benedikt Fluhr. Quasi-Universality of Reeb Graph Distances. In 38th International Symposium on Computational Geometry (SoCG 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 224, pp. 14:1-14:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{bauer_et_al:LIPIcs.SoCG.2022.14,
  author =	{Bauer, Ulrich and Bjerkevik, H\r{a}vard Bakke and Fluhr, Benedikt},
  title =	{{Quasi-Universality of Reeb Graph Distances}},
  booktitle =	{38th International Symposium on Computational Geometry (SoCG 2022)},
  pages =	{14:1--14:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-227-3},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{224},
  editor =	{Goaoc, Xavier and Kerber, Michael},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2022.14},
  URN =		{urn:nbn:de:0030-drops-160221},
  doi =		{10.4230/LIPIcs.SoCG.2022.14},
  annote =	{Keywords: Reeb graphs, contour trees, merge trees, distances, universality, interleaving distance, functional distortion distance, functional contortion distance}
}
Document
Track B: Automata, Logic, Semantics, and Theory of Programming
DOI: 10.4230/LIPIcs.ICALP.2020.112
Two Variable Logic with Ultimately Periodic Counting

Authors: Michael Benedikt, Egor V. Kostylev, and Tony Tan

Published in: LIPIcs, Volume 168, 47th International Colloquium on Automata, Languages, and Programming (ICALP 2020)

Abstract
We consider the extension of FO² with quantifiers that state that the number of elements where a formula holds should belong to a given ultimately periodic set. We show that both satisfiability and finite satisfiability of the logic are decidable. We also show that the spectrum of any sentence is definable in Presburger arithmetic. In the process we present several refinements to the "biregular graph method". In this method, decidability issues concerning two-variable logics are reduced to questions about Presburger definability of integer vectors associated with partitioned graphs, where nodes in a partition satisfy certain constraints on their in- and out-degrees.
Cite as

Michael Benedikt, Egor V. Kostylev, and Tony Tan. Two Variable Logic with Ultimately Periodic Counting. In 47th International Colloquium on Automata, Languages, and Programming (ICALP 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 168, pp. 112:1-112:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{benedikt_et_al:LIPIcs.ICALP.2020.112,
  author =	{Benedikt, Michael and Kostylev, Egor V. and Tan, Tony},
  title =	{{Two Variable Logic with Ultimately Periodic Counting}},
  booktitle =	{47th International Colloquium on Automata, Languages, and Programming (ICALP 2020)},
  pages =	{112:1--112:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-138-2},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{168},
  editor =	{Czumaj, Artur and Dawar, Anuj and Merelli, Emanuela},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2020.112},
  URN =		{urn:nbn:de:0030-drops-125197},
  doi =		{10.4230/LIPIcs.ICALP.2020.112},
  annote =	{Keywords: Presburger Arithmetic, Two-variable logic}
}
Document
DOI: 10.4230/LIPIcs.AofA.2020.10
Cut Vertices in Random Planar Maps

Authors: Michael Drmota, Marc Noy, and Benedikt Stufler

Published in: LIPIcs, Volume 159, 31st International Conference on Probabilistic, Combinatorial and Asymptotic Methods for the Analysis of Algorithms (AofA 2020)

Abstract
The main goal of this paper is to determine the asymptotic behavior of the number X_n of cut-vertices in random planar maps with n edges. It is shown that X_n/n → c in probability (for some explicit c>0). For so-called subcritial subclasses of planar maps like outerplanar maps we obtain a central limit theorem, too.
Cite as

Michael Drmota, Marc Noy, and Benedikt Stufler. Cut Vertices in Random Planar Maps. In 31st International Conference on Probabilistic, Combinatorial and Asymptotic Methods for the Analysis of Algorithms (AofA 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 159, pp. 10:1-10:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{drmota_et_al:LIPIcs.AofA.2020.10,
  author =	{Drmota, Michael and Noy, Marc and Stufler, Benedikt},
  title =	{{Cut Vertices in Random Planar Maps}},
  booktitle =	{31st International Conference on Probabilistic, Combinatorial and Asymptotic Methods for the Analysis of Algorithms (AofA 2020)},
  pages =	{10:1--10:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-147-4},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{159},
  editor =	{Drmota, Michael and Heuberger, Clemens},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.AofA.2020.10},
  URN =		{urn:nbn:de:0030-drops-120403},
  doi =		{10.4230/LIPIcs.AofA.2020.10},
  annote =	{Keywords: random planar maps, cut vertices, generating functions, local graph limits}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2020.13
Distribution Constraints: The Chase for Distributed Data

Authors: Gaetano Geck, Frank Neven, and Thomas Schwentick

Published in: LIPIcs, Volume 155, 23rd International Conference on Database Theory (ICDT 2020)

Abstract
This paper introduces a declarative framework to specify and reason about distributions of data over computing nodes in a distributed setting. More specifically, it proposes distribution constraints which are tuple and equality generating dependencies (tgds and egds) extended with node variables ranging over computing nodes. In particular, they can express co-partitioning constraints and constraints about range-based data distributions by using comparison atoms. The main technical contribution is the study of the implication problem of distribution constraints. While implication is undecidable in general, relevant fragments of so-called data-full constraints are exhibited for which the corresponding implication problems are complete for EXPTIME, PSPACE and NP. These results yield bounds on deciding parallel-correctness for conjunctive queries in the presence of distribution constraints.
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Gaetano Geck, Frank Neven, and Thomas Schwentick. Distribution Constraints: The Chase for Distributed Data. In 23rd International Conference on Database Theory (ICDT 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 155, pp. 13:1-13:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{geck_et_al:LIPIcs.ICDT.2020.13,
  author =	{Geck, Gaetano and Neven, Frank and Schwentick, Thomas},
  title =	{{Distribution Constraints: The Chase for Distributed Data}},
  booktitle =	{23rd International Conference on Database Theory (ICDT 2020)},
  pages =	{13:1--13:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-139-9},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{155},
  editor =	{Lutz, Carsten and Jung, Jean Christoph},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2020.13},
  URN =		{urn:nbn:de:0030-drops-119378},
  doi =		{10.4230/LIPIcs.ICDT.2020.13},
  annote =	{Keywords: tuple-generating dependencies, chase, conjunctive queries, distributed evaluation}
}
Document
DOI: 10.4230/DagRep.9.9.1
Logic and Learning (Dagstuhl Seminar 19361)

Authors: Michael Benedikt, Kristian Kersting, Phokion G. Kolaitis, and Daniel Neider

Published in: Dagstuhl Reports, Volume 9, Issue 9 (2020)

Abstract
The goal of building truly intelligent systems has forever been a central problem in computer science. While logic-based approaches of yore have had their successes and failures, the era of machine learning, specifically deep learning is also coming upon significant challenges. There is a growing consensus that the inductive reasoning and complex, high-dimensional pattern recognition capabilities of deep learning models need to be combined with symbolic (even programmatic), deductive capabilities traditionally developed in the logic and automated reasoning communities in order to achieve the next step towards building intelligent systems, including making progress at the frontier of hard problems such as explainable AI. However, these communities tend to be quite separate and interact only minimally, often at odds with each other upon the subject of the ``correct approach'' to AI. This report documents the efforts of Dagstuhl Seminar 19361 on ``Logic and Learning'' to bring these communities together in order to: (i) bridge the research efforts between them and foster an exchange of ideas in order to create unified formalisms and approaches that bear the advantages of both research methodologies; (ii) review and analyse the progress made across both communities; (iii) understand the subtleties and difficulties involved in solving hard problems using both perspectives; (iv) make attempts towards a consensus on what the hard problems are and what the elements of good solutions to these problems would be. The three focal points of the seminar were the strands of ``Logic for Machine Learning'', ``Machine Learning for Logic'', and ``Logic vs. Machine Learning''. The seminar format consisted of long and short talks, as well as breakout sessions. We summarise the motivations and proceedings of the seminar, and report on the abstracts of the talks and the results of the breakout sessions.
Cite as

Michael Benedikt, Kristian Kersting, Phokion G. Kolaitis, and Daniel Neider. Logic and Learning (Dagstuhl Seminar 19361). In Dagstuhl Reports, Volume 9, Issue 9, pp. 1-22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@Article{benedikt_et_al:DagRep.9.9.1,
  author =	{Benedikt, Michael and Kersting, Kristian and Kolaitis, Phokion G. and Neider, Daniel},
  title =	{{Logic and Learning (Dagstuhl Seminar 19361)}},
  pages =	{1--22},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2020},
  volume =	{9},
  number =	{9},
  editor =	{Benedikt, Michael and Kersting, Kristian and Kolaitis, Phokion G. and Neider, Daniel},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.9.9.1},
  URN =		{urn:nbn:de:0030-drops-118425},
  doi =		{10.4230/DagRep.9.9.1},
  annote =	{Keywords: Artificial Intelligence, Automated reasoning, Databases, Deep Learning, Inductive Logic Programming, Logic, Logic and Learning, Logic for Machine Learning, Logic vs. Machine Learning, Machine Learning, Machine Learning for Logic, Neurosymbolic methods}
}
Document
DOI: 10.4230/LIPIcs.ICALP.2017.107
Characterizing Definability in Decidable Fixpoint Logics

Authors: Michael Benedikt, Pierre Bourhis, and Michael Vanden Boom

Published in: LIPIcs, Volume 80, 44th International Colloquium on Automata, Languages, and Programming (ICALP 2017)

Abstract
We look at characterizing which formulas are expressible in rich decidable logics such as guarded fixpoint logic, unary negation fixpoint logic, and guarded negation fixpoint logic. We consider semantic characterizations of definability, as well as effective characterizations. Our algorithms revolve around a finer analysis of the tree-model property and a refinement of the method of moving back-and-forth between relational logics and logics over trees.
Cite as

Michael Benedikt, Pierre Bourhis, and Michael Vanden Boom. Characterizing Definability in Decidable Fixpoint Logics. In 44th International Colloquium on Automata, Languages, and Programming (ICALP 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 80, pp. 107:1-107:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{benedikt_et_al:LIPIcs.ICALP.2017.107,
  author =	{Benedikt, Michael and Bourhis, Pierre and Vanden Boom, Michael},
  title =	{{Characterizing Definability in Decidable Fixpoint Logics}},
  booktitle =	{44th International Colloquium on Automata, Languages, and Programming (ICALP 2017)},
  pages =	{107:1--107:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-041-5},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{80},
  editor =	{Chatzigiannakis, Ioannis and Indyk, Piotr and Kuhn, Fabian and Muscholl, Anca},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2017.107},
  URN =		{urn:nbn:de:0030-drops-74062},
  doi =		{10.4230/LIPIcs.ICALP.2017.107},
  annote =	{Keywords: Guarded logics, bisimulation, definability, automata}
}
Document
Complete Volume
DOI: 10.4230/LIPIcs.ICDT.2017
LIPIcs, Volume 68, ICDT'17, Complete Volume

Authors: Michael Benedikt and Giorgio Orsi

Published in: LIPIcs, Volume 68, 20th International Conference on Database Theory (ICDT 2017)

Abstract
LIPIcs, Volume 68, ICDT'17, Complete Volume
Cite as

20th International Conference on Database Theory (ICDT 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 68, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@Proceedings{benedikt_et_al:LIPIcs.ICDT.2017,
  title =	{{LIPIcs, Volume 68, ICDT'17, Complete Volume}},
  booktitle =	{20th International Conference on Database Theory (ICDT 2017)},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-024-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{68},
  editor =	{Benedikt, Michael and Orsi, Giorgio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2017},
  URN =		{urn:nbn:de:0030-drops-70689},
  doi =		{10.4230/LIPIcs.ICDT.2017},
  annote =	{Keywords: Database Management, Normal Forms, Schema and Subschema, Query Languages, \lbrackSystems\rbrack Query Processing, Relational Databases, Distributed Databases}
}
Document
Front Matter
DOI: 10.4230/LIPIcs.ICDT.2017.0
Front Matter, Table of Contents, Preface, Conference Organization, List of Authors

Authors: Michael Benedikt and Giorgio Orsi

Published in: LIPIcs, Volume 68, 20th International Conference on Database Theory (ICDT 2017)

Abstract
Front Matter, Table of Contents, Preface, Conference Organization, List of Authors
Cite as

20th International Conference on Database Theory (ICDT 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 68, pp. 0:i-0:xii, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{benedikt_et_al:LIPIcs.ICDT.2017.0,
  author =	{Benedikt, Michael and Orsi, Giorgio},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization, List of Authors}},
  booktitle =	{20th International Conference on Database Theory (ICDT 2017)},
  pages =	{0:i--0:xii},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-024-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{68},
  editor =	{Benedikt, Michael and Orsi, Giorgio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2017.0},
  URN =		{urn:nbn:de:0030-drops-70446},
  doi =		{10.4230/LIPIcs.ICDT.2017.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization, List of Authors}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2017.1
Rewritability in Monadic Disjunctive Datalog, MMSNP, and Expressive Description Logics (Invited Talk)

Authors: Cristina Feier, Antti Kuusisto, and Carsten Lutz

Published in: LIPIcs, Volume 68, 20th International Conference on Database Theory (ICDT 2017)

Abstract
We study rewritability of monadic disjunctive Datalog programs, (the complements of) MMSNP sentences, and ontology-mediated queries (OMQs) based on expressive description logics of the ALC family and on conjunctive queries. We show that rewritability into FO and into monadic Datalog (MDLog) are decidable, and that rewritability into Datalog is decidable when the original query satisfies a certain condition related to equality. We establish 2NExpTime-completeness for all studied problems except rewritability into MDLog for which there remains a gap between 2NExpTime and 3ExpTime. We also analyze the shape of rewritings, which in the MMSNP case correspond to obstructions, and give a new construction of canonical Datalog programs that is more elementary than existing ones and also applies to non-Boolean queries.
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Cristina Feier, Antti Kuusisto, and Carsten Lutz. Rewritability in Monadic Disjunctive Datalog, MMSNP, and Expressive Description Logics (Invited Talk). In 20th International Conference on Database Theory (ICDT 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 68, pp. 1:1-1:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{feier_et_al:LIPIcs.ICDT.2017.1,
  author =	{Feier, Cristina and Kuusisto, Antti and Lutz, Carsten},
  title =	{{Rewritability in Monadic Disjunctive Datalog, MMSNP, and Expressive Description Logics}},
  booktitle =	{20th International Conference on Database Theory (ICDT 2017)},
  pages =	{1:1--1:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-024-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{68},
  editor =	{Benedikt, Michael and Orsi, Giorgio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2017.1},
  URN =		{urn:nbn:de:0030-drops-70636},
  doi =		{10.4230/LIPIcs.ICDT.2017.1},
  annote =	{Keywords: FO-Rewritability, MDDLog, MMSNP, DL, ontology mediated queries}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2017.2
Graphs, Hypergraphs, and the Complexity of Conjunctive Database Queries (Invited Talk)

Authors: Dániel Marx

Published in: LIPIcs, Volume 68, 20th International Conference on Database Theory (ICDT 2017)

Abstract
The complexity of evaluating conjunctive queries can depend significantly on the structure of the query. For example, it is well known that various notions of acyclicity can make the evaluation problem tractable. More generally, it seems that the complexity is connected to the "treelikeness" of the graph or hypergraph describing the query structure. In the lecture, we will review some of the notions of treelikeness that were proposed in the literature and how they are relevant for the complexity of evaluating conjunctive queries and related problems.
Cite as

Dániel Marx. Graphs, Hypergraphs, and the Complexity of Conjunctive Database Queries (Invited Talk). In 20th International Conference on Database Theory (ICDT 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 68, p. 2:1, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{marx:LIPIcs.ICDT.2017.2,
  author =	{Marx, D\'{a}niel},
  title =	{{Graphs, Hypergraphs, and the Complexity of Conjunctive Database Queries}},
  booktitle =	{20th International Conference on Database Theory (ICDT 2017)},
  pages =	{2:1--2:1},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-024-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{68},
  editor =	{Benedikt, Michael and Orsi, Giorgio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2017.2},
  URN =		{urn:nbn:de:0030-drops-70652},
  doi =		{10.4230/LIPIcs.ICDT.2017.2},
  annote =	{Keywords: Conjunctive queries, treewidth, complexity}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2017.3
The Smart Crowd - Learning from the Ones Who Know (Invited Talk)

Authors: Tova Milo

Published in: LIPIcs, Volume 68, 20th International Conference on Database Theory (ICDT 2017)

Abstract
One of the foremost challenges for information technology over the last few years has been to explore, understand, and extract useful information from large amounts of data. Some particular tasks such as annotating data or matching entities have been outsourced to human workers for many years. But the last few years have seen the rise of a new research field called crowdsourcing that aims at delegating a wide range of tasks to human workers, building formal frameworks, and improving the efficiency of these processes. In order to provide sound scientific foundations for crowdsourcing and support the development of efficient crowd sourcing processes, adequate formal models and algorithms must be defined. In particular, the models must formalize unique characteristics of crowd-based settings, such as the knowledge of the crowd and crowd-provided data; the interaction with crowd members; the inherent inaccuracies and disagreements in crowd answers; and evaluation metrics that capture the cost and effort of the crowd. Clearly, what may be achieved with the help of the crowd depends heavily on the properties and knowledge of the given crowd. In this talk we will focus on knowledgeable crowds. We will examine the use of such crowds, and in particular domain experts, for assisting solving data management problems. Specifically we will consider three dimensions of the problem: (1) How domain experts can help in improving the data itself, e.g. by gathering missing data and improving the quality of existing data, (2) How they can assist in gathering meta-data that facilitate improved data processing, and (3) How can we find and identify the most relevant crowd for a given data management task.
Cite as

Tova Milo. The Smart Crowd - Learning from the Ones Who Know (Invited Talk). In 20th International Conference on Database Theory (ICDT 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 68, p. 3:1, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{milo:LIPIcs.ICDT.2017.3,
  author =	{Milo, Tova},
  title =	{{The Smart Crowd - Learning from the Ones Who Know}},
  booktitle =	{20th International Conference on Database Theory (ICDT 2017)},
  pages =	{3:1--3:1},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-024-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{68},
  editor =	{Benedikt, Michael and Orsi, Giorgio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2017.3},
  URN =		{urn:nbn:de:0030-drops-70643},
  doi =		{10.4230/LIPIcs.ICDT.2017.3},
  annote =	{Keywords: data management, crowdsourcing}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2017.4
GYM: A Multiround Distributed Join Algorithm

Authors: Foto N. Afrati, Manas R. Joglekar, Christopher M. Re, Semih Salihoglu, and Jeffrey D. Ullman

Published in: LIPIcs, Volume 68, 20th International Conference on Database Theory (ICDT 2017)

Abstract
Multiround algorithms are now commonly used in distributed data processing systems, yet the extent to which algorithms can benefit from running more rounds is not well understood. This paper answers this question for several rounds for the problem of computing the equijoin of n relations. Given any query Q with width w, intersection width iw, input size IN, output size OUT, and a cluster of machines with M=\Omega(IN \frac{1}{\epsilon}) memory available per machine, where \epsilon > 1 and w \ge 1 are constants, we show that: 1. Q can be computed in O(n) rounds with O(n(INw + OUT)2/M) communication cost with high probability. Q can be computed in O(log(n)) rounds with O(n(INmax(w, 3iw) + OUT)2/M) communication cost with high probability. Intersection width is a new notion we introduce for queries and generalized hypertree decompositions (GHDs) of queries that captures how connected the adjacent components of the GHDs are. We achieve our first result by introducing a distributed and generalized version of Yannakakis's algorithm, called GYM. GYM takes as input any GHD of Q with width w and depth d, and computes Q in O(d + log(n)) rounds and O(n (INw + OUT)2/M) communication cost. We achieve our second result by showing how to construct GHDs of Q with width max(w, 3iw) and depth O(log(n)). We describe another technique to construct GHDs with longer widths and lower depths, demonstrating other tradeoffs one can make between communication and the number of rounds.
Cite as

Foto N. Afrati, Manas R. Joglekar, Christopher M. Re, Semih Salihoglu, and Jeffrey D. Ullman. GYM: A Multiround Distributed Join Algorithm. In 20th International Conference on Database Theory (ICDT 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 68, pp. 4:1-4:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{afrati_et_al:LIPIcs.ICDT.2017.4,
  author =	{Afrati, Foto N. and Joglekar, Manas R. and Re, Christopher M. and Salihoglu, Semih and Ullman, Jeffrey D.},
  title =	{{GYM: A Multiround Distributed Join Algorithm}},
  booktitle =	{20th International Conference on Database Theory (ICDT 2017)},
  pages =	{4:1--4:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-024-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{68},
  editor =	{Benedikt, Michael and Orsi, Giorgio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2017.4},
  URN =		{urn:nbn:de:0030-drops-70462},
  doi =		{10.4230/LIPIcs.ICDT.2017.4},
  annote =	{Keywords: Joins, Yannakakis, Bulk Synchronous Processing, GHDs}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2017.5
Top-k Querying of Unknown Values under Order Constraints

Authors: Antoine Amarilli, Yael Amsterdamer, Tova Milo, and Pierre Senellart

Published in: LIPIcs, Volume 68, 20th International Conference on Database Theory (ICDT 2017)

Abstract
Many practical scenarios make it necessary to evaluate top-k queries over data items with partially unknown values. This paper considers a setting where the values are taken from a numerical domain, and where some partial order constraints are given over known and unknown values: under these constraints, we assume that all possible worlds are equally likely. Our work is the first to propose a principled scheme to derive the value distributions and expected values of unknown items in this setting, with the goal of computing estimated top-k results by interpolating the unknown values from the known ones. We study the complexity of this general task, and show tight complexity bounds, proving that the problem is intractable, but can be tractably approximated. We then consider the case of tree-shaped partial orders, where we show a constructive PTIME solution. We also compare our problem setting to other top-k definitions on uncertain data.
Cite as

Antoine Amarilli, Yael Amsterdamer, Tova Milo, and Pierre Senellart. Top-k Querying of Unknown Values under Order Constraints. In 20th International Conference on Database Theory (ICDT 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 68, pp. 5:1-5:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{amarilli_et_al:LIPIcs.ICDT.2017.5,
  author =	{Amarilli, Antoine and Amsterdamer, Yael and Milo, Tova and Senellart, Pierre},
  title =	{{Top-k Querying of Unknown Values under Order Constraints}},
  booktitle =	{20th International Conference on Database Theory (ICDT 2017)},
  pages =	{5:1--5:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-024-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{68},
  editor =	{Benedikt, Michael and Orsi, Giorgio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2017.5},
  URN =		{urn:nbn:de:0030-drops-70457},
  doi =		{10.4230/LIPIcs.ICDT.2017.5},
  annote =	{Keywords: uncertainty, partial order, unknown values, crowdsourcing, interpolation}
}
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