33 Search Results for "Arenas, Marcelo"

Volume

LIPIcs, Volume 31

18th International Conference on Database Theory (ICDT 2015)

ICDT 2015, March 23-27, 2015, Brussels, Belgium

Editors: Marcelo Arenas and Martín Ugarte

Document
DOI: 10.4230/LIPIcs.ICDT.2024.15
Conjunctive Queries on Probabilistic Graphs: The Limits of Approximability

Authors: Antoine Amarilli, Timothy van Bremen, and Kuldeep S. Meel

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

Abstract
Query evaluation over probabilistic databases is a notoriously intractable problem - not only in combined complexity, but for many natural queries in data complexity as well [Antoine Amarilli et al., 2017; Nilesh N. Dalvi and Dan Suciu, 2012]. This motivates the study of probabilistic query evaluation through the lens of approximation algorithms, and particularly of combined FPRASes, whose runtime is polynomial in both the query and instance size. In this paper, we focus on tuple-independent probabilistic databases over binary signatures, which can be equivalently viewed as probabilistic graphs. We study in which cases we can devise combined FPRASes for probabilistic query evaluation in this setting. We settle the complexity of this problem for a variety of query and instance classes, by proving both approximability and (conditional) inapproximability results. This allows us to deduce many corollaries of possible independent interest. For example, we show how the results of [Marcelo Arenas et al., 2021] on counting fixed-length strings accepted by an NFA imply the existence of an FPRAS for the two-terminal network reliability problem on directed acyclic graphs: this was an open problem until now [Rico Zenklusen and Marco Laumanns, 2011]. We also show that one cannot extend a recent result [Timothy van Bremen and Kuldeep S. Meel, 2023] that gives a combined FPRAS for self-join-free conjunctive queries of bounded hypertree width on probabilistic databases: neither the bounded-hypertree-width condition nor the self-join-freeness hypothesis can be relaxed. Finally, we complement all our inapproximability results with unconditional lower bounds, showing that DNNF provenance circuits must have at least moderately exponential size in combined complexity.
Cite as

Antoine Amarilli, Timothy van Bremen, and Kuldeep S. Meel. Conjunctive Queries on Probabilistic Graphs: The Limits of Approximability. In 27th International Conference on Database Theory (ICDT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 290, pp. 15:1-15:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{amarilli_et_al:LIPIcs.ICDT.2024.15,
  author =	{Amarilli, Antoine and van Bremen, Timothy and Meel, Kuldeep S.},
  title =	{{Conjunctive Queries on Probabilistic Graphs: The Limits of Approximability}},
  booktitle =	{27th International Conference on Database Theory (ICDT 2024)},
  pages =	{15:1--15:20},
  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.2024.15},
  URN =		{urn:nbn:de:0030-drops-197978},
  doi =		{10.4230/LIPIcs.ICDT.2024.15},
  annote =	{Keywords: Probabilistic query evaluation, tuple-independent databases, approximation}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2022.2
Counting the Solutions to a Query (Invited Talk)

Authors: Marcelo Arenas

Published in: LIPIcs, Volume 220, 25th International Conference on Database Theory (ICDT 2022)

Abstract
In this talk, we consider the problem of counting the solutions to a query. Our first motivating scenario is the use of regular expressions to extract paths from a graph database. More specifically, given a graph database D, a regular expression r and a natural number n, consider the problem of counting the number of paths p in D such that p conforms to r and the length of p is n. This problem is known to be hard, namely #P-complete. In this talk, we show that this problem admits a fully polynomial-time randomized approximation scheme (FPRAS). Remarkably, the key idea to prove this result is to show that the fundamental problem #NFA admits an FPRAS, where #NFA is the problem of counting the number of strings of length n accepted by a non-deterministic finite automaton (NFA). While this problem is known to be #P-complete and, more precisely, SpanL-complete, it was open whether this problem admits an FPRAS. In this work, we solve this open problem and obtain as a welcome corollary that every function in SpanL admits an FPRAS. As a second motivating scenario, we consider the widely used class of conjunctive queries over relational databases. More specifically, for every class C of conjunctive queries with bounded treewidth, we introduce the first FPRAS for counting the answers to a query in C. In fact, our FPRAS is more general, and also applies to conjunctive queries with bounded hypertree width, as well as unions of such queries. As for the case of graph databases, the key ingredient in our proof is the resolution of a fundamental counting problem from automata theory. Specifically, we show that the problem #TA admits an FPRAS, where #TA is the problem of counting the number of trees of size n accepted by a tree automaton (TA). This talk is based on the results presented in [Marcelo Arenas et al., 2021; Marcelo Arenas et al., 2021].
Cite as

Marcelo Arenas. Counting the Solutions to a Query (Invited Talk). In 25th International Conference on Database Theory (ICDT 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 220, p. 2:1, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{arenas:LIPIcs.ICDT.2022.2,
  author =	{Arenas, Marcelo},
  title =	{{Counting the Solutions to a Query}},
  booktitle =	{25th International Conference on Database Theory (ICDT 2022)},
  pages =	{2:1--2:1},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-223-5},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{220},
  editor =	{Olteanu, Dan and Vortmeier, Nils},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2022.2},
  URN =		{urn:nbn:de:0030-drops-158763},
  doi =		{10.4230/LIPIcs.ICDT.2022.2},
  annote =	{Keywords: Counting, query answering, fully polynomial-time randomized approximation scheme}
}
Document
DOI: 10.4230/LIPIcs.STACS.2020.54
Cryptocurrency Mining Games with Economic Discount and Decreasing Rewards

Authors: Marcelo Arenas, Juan Reutter, Etienne Toussaint, Martín Ugarte, Francisco Vial, and Domagoj Vrgoč

Published in: LIPIcs, Volume 154, 37th International Symposium on Theoretical Aspects of Computer Science (STACS 2020)

Abstract
In the consensus protocols used in most cryptocurrencies, participants called miners must find valid blocks of transactions and append them to a shared tree-like data structure. Ideally, the rules of the protocol should ensure that miners maximize their gains if they follow a default strategy, which consists on appending blocks only to the longest branch of the tree, called the blockchain. Our goal is to understand under which circumstances are miners encouraged to follow the default strategy. Unfortunately, most of the existing models work with simplified payoff functions, without considering the possibility that rewards decrease over time because of the game rules (like in Bitcoin), nor integrating the fact that a miner naturally prefers to be paid earlier than later (the economic concept of discount). In order to integrate these factors, we consider a more general model where issues such as economic discount and decreasing rewards can be set as parameters of an infinite stochastic game. In this model, we study the limit situation in which a miner does not receive a full reward for a block if it stops being in the blockchain. We show that if rewards are not decreasing, then miners do not have incentives to create new branches, no matter how high their computational power is. On the other hand, when working with decreasing rewards similar to those in Bitcoin, we show that miners have an incentive to create such branches. Nevertheless, this incentive only occurs when a miner controls a proportion of the computational power which is close to half of the computational power of the entire network.
Cite as

Marcelo Arenas, Juan Reutter, Etienne Toussaint, Martín Ugarte, Francisco Vial, and Domagoj Vrgoč. Cryptocurrency Mining Games with Economic Discount and Decreasing Rewards. In 37th International Symposium on Theoretical Aspects of Computer Science (STACS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 154, pp. 54:1-54:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{arenas_et_al:LIPIcs.STACS.2020.54,
  author =	{Arenas, Marcelo and Reutter, Juan and Toussaint, Etienne and Ugarte, Mart{\'\i}n and Vial, Francisco and Vrgo\v{c}, Domagoj},
  title =	{{Cryptocurrency Mining Games with Economic Discount and Decreasing Rewards}},
  booktitle =	{37th International Symposium on Theoretical Aspects of Computer Science (STACS 2020)},
  pages =	{54:1--54:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-140-5},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{154},
  editor =	{Paul, Christophe and Bl\"{a}ser, Markus},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2020.54},
  URN =		{urn:nbn:de:0030-drops-119150},
  doi =		{10.4230/LIPIcs.STACS.2020.54},
  annote =	{Keywords: cryptocurrency, game theory, cryptomining, economic discount, decreasing rewards}
}
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/DagRep.6.4.39
Foundations of Data Management (Dagstuhl Perspectives Workshop 16151)

Authors: Marcelo Arenas, Richard Hull, Wim Marten, Tova Milo, and Thomas Schwentick

Published in: Dagstuhl Reports, Volume 6, Issue 4 (2016)

Abstract
In this Workshop we have explored the degree to which principled foundations are crucial to the long-term success and effectiveness of the new generation of data management paradigms and applications, and investigated what forms of research need to be pursued to develop and advance these foundations. The workshop brought together specialists from the existing database theory community, and from adjoining areas, particularly from various subdisciplines within the Big Data community, to understand the challenge areas that might be resolved through principled foundations and mathematical theory.
Cite as

Marcelo Arenas, Richard Hull, Wim Marten, Tova Milo, and Thomas Schwentick. Foundations of Data Management (Dagstuhl Perspectives Workshop 16151). In Dagstuhl Reports, Volume 6, Issue 4, pp. 39-56, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

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@Article{arenas_et_al:DagRep.6.4.39,
  author =	{Arenas, Marcelo and Hull, Richard and Marten, Wim and Milo, Tova and Schwentick, Thomas},
  title =	{{Foundations of Data Management (Dagstuhl Perspectives Workshop 16151)}},
  pages =	{39--56},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2016},
  volume =	{6},
  number =	{4},
  editor =	{Arenas, Marcelo and Hull, Richard and Marten, Wim and Milo, Tova and Schwentick, Thomas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.6.4.39},
  URN =		{urn:nbn:de:0030-drops-61526},
  doi =		{10.4230/DagRep.6.4.39},
  annote =	{Keywords: Foundations of data management, Principles of databases}
}
Document
Complete Volume
DOI: 10.4230/LIPIcs.ICDT.2015
LIPIcs, Volume 31, ICDT'15, Complete Volume

Authors: Marcelo Arenas and Martín Ugarte

Published in: LIPIcs, Volume 31, 18th International Conference on Database Theory (ICDT 2015)

Abstract
LIPIcs, Volume 31, ICDT'15, Complete Volume
Cite as

18th International Conference on Database Theory (ICDT 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 31, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@Proceedings{arenas_et_al:LIPIcs.ICDT.2015,
  title =	{{LIPIcs, Volume 31, ICDT'15, Complete Volume}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2015},
  URN =		{urn:nbn:de:0030-drops-50077},
  doi =		{10.4230/LIPIcs.ICDT.2015},
  annote =	{Keywords: Database Management, Normal forms, Schema and subschema, Query languages, Query processing, Relational databases, Distributed databases, Heterogeneous Databases, Online Information Services, Miscellaneous – Privacy, Office Automation: Workflow management, Performance Analysis and Design Aids: Formal}
}
Document
Front Matter
DOI: 10.4230/LIPIcs.ICDT.2015.i
Title, Table of Contents, Preface, ICDT 2015 Test of Time Award, Organization, External Reviewers, List of Authors

Authors: Marcelo Arenas and Martín Ugarte

Published in: LIPIcs, Volume 31, 18th International Conference on Database Theory (ICDT 2015)

Abstract
Title, Table of Contents, Preface, ICDT 2015 Test of Time Award, Organization, External Reviewers, List of Authors
Cite as

18th International Conference on Database Theory (ICDT 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 31, pp. i-xvi, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@InProceedings{arenas_et_al:LIPIcs.ICDT.2015.i,
  author =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  title =	{{Title, Table of Contents, Preface, ICDT 2015 Test of Time Award, Organization, External Reviewers, List of Authors}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  pages =	{i--xvi},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2015.i},
  URN =		{urn:nbn:de:0030-drops-50002},
  doi =		{10.4230/LIPIcs.ICDT.2015.i},
  annote =	{Keywords: Title, Table of Contents, Preface, ICDT 2015 Test of Time Award, Organization, External Reviewers, List of Authors}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2015.1
The Confounding Problem of Private Data Release (Invited Talk)

Authors: Graham Cormode

Published in: LIPIcs, Volume 31, 18th International Conference on Database Theory (ICDT 2015)

Abstract
The demands to make data available are growing ever louder, including open data initiatives and "data monetization". But the problem of doing so without disclosing confidential information is a subtle and difficult one. Is "private data release" an oxymoron? This paper (accompanying an invited talk) aims to delve into the motivations of data release, explore the challenges, and outline some of the current statistical approaches developed in response to this confounding problem.
Cite as

Graham Cormode. The Confounding Problem of Private Data Release (Invited Talk). In 18th International Conference on Database Theory (ICDT 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 31, pp. 1-12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@InProceedings{cormode:LIPIcs.ICDT.2015.1,
  author =	{Cormode, Graham},
  title =	{{The Confounding Problem of Private Data Release}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  pages =	{1--12},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2015.1},
  URN =		{urn:nbn:de:0030-drops-49977},
  doi =		{10.4230/LIPIcs.ICDT.2015.1},
  annote =	{Keywords: privacy, anonymization, data release}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2015.13
Using Locality for Efficient Query Evaluation in Various Computation Models (Invited Talk)

Authors: Nicole Schweikardt

Published in: LIPIcs, Volume 31, 18th International Conference on Database Theory (ICDT 2015)

Abstract
In the database theory and logic literature, different notions of locality of queries have been studied, the most prominent being Hanf locality and Gaifman locality. These notions are designed so that, in order to evaluate a local query in a given database, it suffices to look only at small neighbourhoods around tuples of elements that belong to the database. In this talk I want to give a survey of how to use locality for efficient query evaluation in various computation models. In particular, we will take a closer look at how to enumerate query results with constant delay, and at how to evaluate queries in a map-reduce like setting [Neven et al., ICDT 2015] or in Pregel [Malewicz et al., SIGMOD 2010]. Also, we will have a closer look at how to transform a given local query into a form suitable for exploiting its locality.
Cite as

Nicole Schweikardt. Using Locality for Efficient Query Evaluation in Various Computation Models (Invited Talk). In 18th International Conference on Database Theory (ICDT 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 31, pp. 13-14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@InProceedings{schweikardt:LIPIcs.ICDT.2015.13,
  author =	{Schweikardt, Nicole},
  title =	{{Using Locality for Efficient Query Evaluation in Various Computation Models}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  pages =	{13--14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2015.13},
  URN =		{urn:nbn:de:0030-drops-49987},
  doi =		{10.4230/LIPIcs.ICDT.2015.13},
  annote =	{Keywords: query evaluation, locality}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2015.15
Large-Scale Similarity Joins With Guarantees (Invited Talk)

Authors: Rasmus Pagh

Published in: LIPIcs, Volume 31, 18th International Conference on Database Theory (ICDT 2015)

Abstract
The ability to handle noisy or imprecise data is becoming increasingly important in computing. In the database community the notion of similarity join has been studied extensively, yet existing solutions have offered weak performance guarantees. Either they are based on deterministic filtering techniques that often, but not always, succeed in reducing computational costs, or they are based on randomized techniques that have improved guarantees on computational cost but come with a probability of not returning the correct result. The aim of this paper is to give an overview of randomized techniques for high-dimensional similarity search, and discuss recent advances towards making these techniques more widely applicable by eliminating probability of error and improving the locality of data access.
Cite as

Rasmus Pagh. Large-Scale Similarity Joins With Guarantees (Invited Talk). In 18th International Conference on Database Theory (ICDT 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 31, pp. 15-24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@InProceedings{pagh:LIPIcs.ICDT.2015.15,
  author =	{Pagh, Rasmus},
  title =	{{Large-Scale Similarity Joins With Guarantees}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  pages =	{15--24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2015.15},
  URN =		{urn:nbn:de:0030-drops-49995},
  doi =		{10.4230/LIPIcs.ICDT.2015.15},
  annote =	{Keywords: Similarity join, filtering, locality-sensitive hashing, recall}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2015.25
A Declarative Framework for Linking Entities

Authors: Douglas Burdick, Ronald Fagin, Phokion G. Kolaitis, Lucian Popa, and Wang-Chiew Tan

Published in: LIPIcs, Volume 31, 18th International Conference on Database Theory (ICDT 2015)

Abstract
The aim of this paper is to introduce and develop a truly declarative framework for entity linking and, in particular, for entity resolution. As in some earlier approaches, our framework is based on the systematic use of constraints. However, the constraints we adopt are link-to-source constraints, unlike in earlier approaches where source-to-link constraints were used to dictate how to generate links. Our approach makes it possible to focus entirely on the intended properties of the outcome of entity linking, thus separating the constraints from any procedure of how to achieve that outcome. The core language consists of link-to-source constraints that specify the desired properties of a link relation in terms of source relations and built-in predicates such as similarity measures. A key feature of the link-to-source constraints is that they employ disjunction, which enables the declarative listing of all the reasons as to why two entities should be linked. We also consider extensions of the core language that capture collective entity resolution, by allowing inter-dependence between links. We identify a class of "good" solutions for entity linking specifications, which we call maximum-value solutions and which capture the strength of a link by counting the reasons that justify it. We study natural algorithmic problems associated with these solutions, including the problem of enumerating the "good" solutions, and the problem of finding the certain links, which are the links that appear in every "good" solution. We show that these problems are tractable for the core language, but may become intractable once we allow inter-dependence between link relations. We also make some surprising connections between our declarative framework, which is deterministic, and probabilistic approaches such as ones based on Markov Logic Networks.
Cite as

Douglas Burdick, Ronald Fagin, Phokion G. Kolaitis, Lucian Popa, and Wang-Chiew Tan. A Declarative Framework for Linking Entities. In 18th International Conference on Database Theory (ICDT 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 31, pp. 25-43, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@InProceedings{burdick_et_al:LIPIcs.ICDT.2015.25,
  author =	{Burdick, Douglas and Fagin, Ronald and Kolaitis, Phokion G. and Popa, Lucian and Tan, Wang-Chiew},
  title =	{{A Declarative Framework for Linking Entities}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  pages =	{25--43},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2015.25},
  URN =		{urn:nbn:de:0030-drops-49759},
  doi =		{10.4230/LIPIcs.ICDT.2015.25},
  annote =	{Keywords: entity linking, entity resolution, constraints, certain links}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2015.44
Asymptotic Determinacy of Path Queries using Union-of-Paths Views

Authors: Nadime Francis

Published in: LIPIcs, Volume 31, 18th International Conference on Database Theory (ICDT 2015)

Abstract
We consider the view determinacy problem over graph databases for queries defined as (possibly infinite) unions of path queries. These queries select pairs of nodes in a graph that are connected through a path whose length falls in a given set. A view specification is a set of such queries. We say that a view specification V determines a query Q if, for all databases D, the answers to V on D contain enough information to answer Q. Our main result states that, given a view V, there exists an explicit bound that depends on V such that we can decide the determinacy problem for all queries that ask for a path longer than this bound, and provide first-order rewritings for the queries that are determined. We call this notion asymptotic determinacy. As a corollary, we can also compute the set of almost all path queries that are determined by V.
Cite as

Nadime Francis. Asymptotic Determinacy of Path Queries using Union-of-Paths Views. In 18th International Conference on Database Theory (ICDT 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 31, pp. 44-59, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@InProceedings{francis:LIPIcs.ICDT.2015.44,
  author =	{Francis, Nadime},
  title =	{{Asymptotic Determinacy of Path Queries using Union-of-Paths Views}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  pages =	{44--59},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2015.44},
  URN =		{urn:nbn:de:0030-drops-49760},
  doi =		{10.4230/LIPIcs.ICDT.2015.44},
  annote =	{Keywords: Graph databases, Views, Determinacy, Rewriting, Path queries}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2015.60
Games for Active XML Revisited

Authors: Martin Schuster and Thomas Schwentick

Published in: LIPIcs, Volume 31, 18th International Conference on Database Theory (ICDT 2015)

Abstract
The paper studies the rewriting mechanisms for intensional documents in the Active XML framework, abstracted in the form of active context-free games. The safe rewriting problem studied in this paper is to decide whether the first player, Juliet, has a winning strategy for a given game and (nested) word; this corresponds to a successful rewriting strategy for a given intensional document. The paper examines several extensions to active context-free games. The primary extension allows more expressive schemas (namely XML schemas and regular nested word languages) for both target and replacement languages and has the effect that games are played on nested words instead of (flat) words as in previous studies. Other extensions consider validation of input parameters of web services, and an alternative semantics based on insertion of service call results. In general, the complexity of the safe rewriting problem is highly intractable (doubly exponential time), but the paper identifies interesting tractable cases.
Cite as

Martin Schuster and Thomas Schwentick. Games for Active XML Revisited. In 18th International Conference on Database Theory (ICDT 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 31, pp. 60-75, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@InProceedings{schuster_et_al:LIPIcs.ICDT.2015.60,
  author =	{Schuster, Martin and Schwentick, Thomas},
  title =	{{Games for Active XML Revisited}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  pages =	{60--75},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2015.60},
  URN =		{urn:nbn:de:0030-drops-49773},
  doi =		{10.4230/LIPIcs.ICDT.2015.60},
  annote =	{Keywords: Active XML, Computational Complexity, Nested Words, Rewriting Games, Semistructured Data}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2015.76
Answering Conjunctive Queries with Inequalities

Authors: Paraschos Koutris, Tova Milo, Sudeepa Roy, and Dan Suciu

Published in: LIPIcs, Volume 31, 18th International Conference on Database Theory (ICDT 2015)

Abstract
In this parer, we study the complexity of answering conjunctive queries (CQ) with inequalities. In particular, we compare the complexity of the query with and without inequalities. The main contribution of our work is a novel combinatorial technique that enables the use of any Select-Project-Join query plan for a given CQ without inequalities in answering the CQ with inequalities, with an additional factor in running time that only depends on the query. To achieve this, we define a new projection operator that keeps a small representation (independent of the size of the database) of the set of input tuples that map to each tuple in the output of the projection; this representation is used to evaluate all the inequalities in the query. Second, we generalize a result by Papadimitriou-Yannakakis [PODS'97] and give an alternative algorithm based on the color-coding technique [Alon, Yuster and Zwick, PODS'02] to evaluate a CQ with inequalities by using an algorithm for the CQ without inequalities. Third, we investigate the structure of the query graph, inequality graph, and the augmented query graph with inequalities, and show that even if the query and the inequality graphs have bounded treewidth, the augmented graph not only can have an unbounded treewidth but can also be NP-hard to evaluate. Further, we illustrate classes of queries and inequalities where the augmented graphs have unbounded treewidth, but the CQ with inequalities can be evaluated in poly-time. Finally, we give necessary properties and sufficient properties that allow a class of CQs to have poly-time combined complexity with respect to any inequality pattern.
Cite as

Paraschos Koutris, Tova Milo, Sudeepa Roy, and Dan Suciu. Answering Conjunctive Queries with Inequalities. In 18th International Conference on Database Theory (ICDT 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 31, pp. 76-93, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@InProceedings{koutris_et_al:LIPIcs.ICDT.2015.76,
  author =	{Koutris, Paraschos and Milo, Tova and Roy, Sudeepa and Suciu, Dan},
  title =	{{Answering Conjunctive Queries with Inequalities}},
  booktitle =	{18th International Conference on Database Theory (ICDT 2015)},
  pages =	{76--93},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-79-8},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{31},
  editor =	{Arenas, Marcelo and Ugarte, Mart{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2015.76},
  URN =		{urn:nbn:de:0030-drops-49781},
  doi =		{10.4230/LIPIcs.ICDT.2015.76},
  annote =	{Keywords: query evaluation, conjunctive query, inequality, treewidth}
}
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