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Documents authored by Hernich, André


Document
Semantics for Non-Monotone Queries in Data Exchange and Data Integration

Authors: André Hernich

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


Abstract
A fundamental question in data exchange and data integration is how to answer queries that are posed against the target schema, or the global schema, respectively. While the certain answers semantics has proved to be adequate for answering monotone queries, the question concerning an appropriate semantics for non-monotone queries turned out to be more difficult. This article surveys approaches and semantics for answering non-monotone queries in data exchange and data integration.

Cite as

André Hernich. Semantics for Non-Monotone Queries in Data Exchange and Data Integration. In Data Exchange, Integration, and Streams. Dagstuhl Follow-Ups, Volume 5, pp. 161-184, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2013)


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@InCollection{hernich:DFU.Vol5.10452.161,
  author =	{Hernich, Andr\'{e}},
  title =	{{Semantics for Non-Monotone Queries in Data Exchange and Data Integration}},
  booktitle =	{Data Exchange, Integration, and Streams},
  pages =	{161--184},
  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.Vol5.10452.161},
  URN =		{urn:nbn:de:0030-drops-42936},
  doi =		{10.4230/DFU.Vol5.10452.161},
  annote =	{Keywords: certain answers, closed world assumption, deductive databases, universal solutions, core}
}
Document
L-Recursion and a new Logic for Logarithmic Space

Authors: Martin Grohe, Berit Grußien, André Hernich, and Bastian Laubner

Published in: LIPIcs, Volume 12, Computer Science Logic (CSL'11) - 25th International Workshop/20th Annual Conference of the EACSL (2011)


Abstract
We extend first-order logic with counting by a new operator that allows it to formalise a limited form of recursion which can be evaluated in logarithmic space. The resulting logic LREC has a data complexity in LOGSPACE, and it defines LOGSPACE-complete problems like deterministic reachability and Boolean formula evaluation. We prove that LREC is strictly more expressive than deterministic transitive closure logic with counting and incomparable in expressive power with symmetric transitive closure logic STC and transitive closure logic (with or without counting). LREC is strictly contained in fixed-point logic with counting FPC. We also study an extension LREC= of LREC that has nicer closure properties and is more expressive than both LREC and STC, but is still contained in FPC and has a data complexity in LOGSPACE. Our main results are that LREC captures LOGSPACE on the class of directed trees and that LREC= captures LOGSPACE on the class of interval graphs.

Cite as

Martin Grohe, Berit Grußien, André Hernich, and Bastian Laubner. L-Recursion and a new Logic for Logarithmic Space. In Computer Science Logic (CSL'11) - 25th International Workshop/20th Annual Conference of the EACSL. Leibniz International Proceedings in Informatics (LIPIcs), Volume 12, pp. 277-291, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)


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@InProceedings{grohe_et_al:LIPIcs.CSL.2011.277,
  author =	{Grohe, Martin and Gru{\ss}ien, Berit and Hernich, Andr\'{e} and Laubner, Bastian},
  title =	{{L-Recursion and a new Logic for Logarithmic Space}},
  booktitle =	{Computer Science Logic (CSL'11) - 25th International Workshop/20th Annual Conference of the EACSL},
  pages =	{277--291},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-32-3},
  ISSN =	{1868-8969},
  year =	{2011},
  volume =	{12},
  editor =	{Bezem, Marc},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2011.277},
  URN =		{urn:nbn:de:0030-drops-32373},
  doi =		{10.4230/LIPIcs.CSL.2011.277},
  annote =	{Keywords: descriptive complexity, logarithmic space, fixed-point logics}
}
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