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Documents authored by Sallinger, Emanuel


Document
Limits of Schema Mappings

Authors: Phokion G. Kolaitis, Reinhard Pichler, Emanuel Sallinger, and Vadim Savenkov

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


Abstract
Schema mappings have been extensively studied in the context of data exchange and data integration, where they have turned out to be the right level of abstraction for formalizing data inter-operability tasks. Up to now and for the most part, schema mappings have been studied as static objects, in the sense that each time the focus has been on a single schema mapping of interest or, in the case of composition, on a pair of schema mappings of interest. In this paper, we adopt a dynamic viewpoint and embark on a study of sequences of schema mappings and of the limiting behavior of such sequences. To this effect, we first introduce a natural notion of distance on sets of finite target instances that expresses how "close" two sets of target instances are as regards the certain answers of conjunctive queries on these sets. Using this notion of distance, we investigate pointwise limits and uniform limits of sequences of schema mappings, as well as the companion notions of pointwise Cauchy and uniformly Cauchy sequences of schema mappings. We obtain a number of results about the limits of sequences of GAV schema mappings and the limits of sequences of LAV schema mappings that reveal striking differences between these two classes of schema mappings. We also consider the completion of the metric space of sets of target instances and obtain concrete representations of limits of sequences of schema mappings in terms of generalized schema mappings, i.e., schema mappings with infinite target instances as solutions to (finite) source instances.

Cite as

Phokion G. Kolaitis, Reinhard Pichler, Emanuel Sallinger, and Vadim Savenkov. Limits of Schema Mappings. In 19th International Conference on Database Theory (ICDT 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 48, pp. 19:1-19:17, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2016)


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@InProceedings{kolaitis_et_al:LIPIcs.ICDT.2016.19,
  author =	{Kolaitis, Phokion G. and Pichler, Reinhard and Sallinger, Emanuel and Savenkov, Vadim},
  title =	{{Limits of Schema Mappings}},
  booktitle =	{19th International Conference on Database Theory (ICDT 2016)},
  pages =	{19:1--19:17},
  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.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2016.19},
  URN =		{urn:nbn:de:0030-drops-57882},
  doi =		{10.4230/LIPIcs.ICDT.2016.19},
  annote =	{Keywords: Limit, Pointwise convergence, Uniform convergence, Schema mapping}
}
Document
Complexity of Repair Checking and Consistent Query Answering

Authors: Sebastian Arming, Reinhard Pichler, and Emanuel Sallinger

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


Abstract
Inconsistent databases (i.e., databases violating some given set of integrity constraints) may arise in many applications such as, for instance, data integration. Hence, the handling of inconsistent data has evolved as an active field of research. In this paper, we consider two fundamental problems in this context: Repair Checking (RC) and Consistent Query Answering (CQA). So far, these problems have been mainly studied from the point of view of data complexity (where all parts of the input except for the database are considered as fixed). While for some kinds of integrity constraints, also combined complexity (where all parts of the input are allowed to vary) has been considered, for several other kinds of integrity constraints, combined complexity has been left unexplored. Moreover, a more detailed analysis (keeping other parts of the input fixed - e.g., the constraints only) is completely missing. The goal of our work is a thorough analysis of the complexity of the RC and CQA problems. Our contribution is a complete picture of the complexity of these problems for a wide range of integrity constraints. Our analysis thus allows us to get a better understanding of the true sources of complexity.

Cite as

Sebastian Arming, Reinhard Pichler, and Emanuel Sallinger. Complexity of Repair Checking and Consistent Query Answering. In 19th International Conference on Database Theory (ICDT 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 48, pp. 21:1-21:18, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2016)


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@InProceedings{arming_et_al:LIPIcs.ICDT.2016.21,
  author =	{Arming, Sebastian and Pichler, Reinhard and Sallinger, Emanuel},
  title =	{{Complexity of Repair Checking and Consistent Query Answering}},
  booktitle =	{19th International Conference on Database Theory (ICDT 2016)},
  pages =	{21:1--21:18},
  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.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2016.21},
  URN =		{urn:nbn:de:0030-drops-57900},
  doi =		{10.4230/LIPIcs.ICDT.2016.21},
  annote =	{Keywords: inconsistency, consistent query answering, complexity}
}
Document
Reasoning about Schema Mappings

Authors: Emanuel Sallinger

Published in: Dagstuhl Follow-Ups, Volume 5, Data Exchange, Integration, and Streams (2013)


Abstract
Schema mappings are an important tool in several areas of database research. Recently, the topic of reasoning about schema mappings was given attention, in particular revolving around the central concepts of equivalence and optimality. In this chapter, we survey these results. First, we introduce relaxed notions of logical equivalence and show their potential for finding optimized schema mappings. We then look at applications of these concepts to optimization, normalization, and schema mapping management, as well as the boundaries of computability. We conclude by giving a glimpse at reasoning about schema mappings in a broader sense by looking at how to debug schema mappings.

Cite as

Emanuel Sallinger. Reasoning about Schema Mappings. In Data Exchange, Integration, and Streams. Dagstuhl Follow-Ups, Volume 5, pp. 97-127, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)


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@InCollection{sallinger:DFU.Vol5.10452.97,
  author =	{Sallinger, Emanuel},
  title =	{{Reasoning about Schema Mappings}},
  booktitle =	{Data Exchange, Integration, and Streams},
  pages =	{97--127},
  series =	{Dagstuhl Follow-Ups},
  ISBN =	{978-3-939897-61-3},
  ISSN =	{1868-8977},
  year =	{2013},
  volume =	{5},
  editor =	{Kolaitis, Phokion G. and Lenzerini, Maurizio and Schweikardt, Nicole},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DFU.Vol5.10452.97},
  URN =		{urn:nbn:de:0030-drops-42917},
  doi =		{10.4230/DFU.Vol5.10452.97},
  annote =	{Keywords: data exchange, data integration, schema mappings, equivalence, optimality, normalization, schema mapping management}
}
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