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Documents authored by Schnabl, Andreas


Document
The Exact Hardness of Deciding Derivational and Runtime Complexity

Authors: Andreas Schnabl and Jakob Grue Simonsen

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


Abstract
For any class C of computable total functions satisfying some mild conditions, we prove that the following decision problems are complete for the existential part of the second level of the arithmetical hierarchy: (A) Deciding whether a term rewriting system (TRS for short) has runtime complexity bounded by a function in C. (B) Deciding whether a TRS has derivational complexity bounded by a function in C. In particular, the problems of deciding whether a TRS has polynomially (exponentially) bounded runtime complexity (respectively derivational complexity) are complete for this level of the arithmetical ierarchy. This places deciding polynomial derivational or runtime complexity of TRSs at the same level as deciding nontermination or nonconfluence of TRSs. We proceed to show that the related problem of deciding for a single computable function f whether a TRS has runtime complexity bounded from above by f is complete for the universal part of the first level of the arithmetical hierarchy. We further prove that analysing the implicit complexity of TRSs is even more difficult: The problem of deciding whether a TRS accepts a language of terms accepted by some TRS with runtime complexity bounded by a function in C is complete for the existential part of the third level of the arithmetical hierarchy. All of our results are easily extended to the notion of minimal complexity (where the length of shortest reductions to normal form is considered) and remain valid under any computable reduction strategy. Finally, all results hold both for unrestricted TRSs and for the class of orthogonal TRSs.

Cite as

Andreas Schnabl and Jakob Grue Simonsen. The Exact Hardness of Deciding Derivational and Runtime Complexity. In Computer Science Logic (CSL'11) - 25th International Workshop/20th Annual Conference of the EACSL. Leibniz International Proceedings in Informatics (LIPIcs), Volume 12, pp. 481-495, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)


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@InProceedings{schnabl_et_al:LIPIcs.CSL.2011.481,
  author =	{Schnabl, Andreas and Simonsen, Jakob Grue},
  title =	{{The Exact Hardness of Deciding Derivational and Runtime Complexity}},
  booktitle =	{Computer Science Logic (CSL'11) - 25th International Workshop/20th Annual Conference of the EACSL},
  pages =	{481--495},
  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.2011.481},
  URN =		{urn:nbn:de:0030-drops-32516},
  doi =		{10.4230/LIPIcs.CSL.2011.481},
  annote =	{Keywords: term rewriting, derivational complexity, arithmetical hierarchy}
}
Document
Termination Proofs in the Dependency Pair Framework May Induce Multiple Recursive Derivational Complexity

Authors: Georg Moser and Andreas Schnabl

Published in: LIPIcs, Volume 10, 22nd International Conference on Rewriting Techniques and Applications (RTA'11) (2011)


Abstract
We study the complexity of rewrite systems shown terminating via the dependency pair framework using processors for reduction pairs, dependency graphs, or the subterm criterion. The complexity of such systems is bounded by a multiple recursive function, provided the complexity induced by the employed base techniques is at most multiple recursive. Moreover this upper bound is tight.

Cite as

Georg Moser and Andreas Schnabl. Termination Proofs in the Dependency Pair Framework May Induce Multiple Recursive Derivational Complexity. In 22nd International Conference on Rewriting Techniques and Applications (RTA'11). Leibniz International Proceedings in Informatics (LIPIcs), Volume 10, pp. 235-250, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)


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@InProceedings{moser_et_al:LIPIcs.RTA.2011.235,
  author =	{Moser, Georg and Schnabl, Andreas},
  title =	{{Termination Proofs in the Dependency Pair Framework May Induce Multiple Recursive Derivational Complexity}},
  booktitle =	{22nd International Conference on Rewriting Techniques and Applications (RTA'11)},
  pages =	{235--250},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-30-9},
  ISSN =	{1868-8969},
  year =	{2011},
  volume =	{10},
  editor =	{Schmidt-Schauss, Manfred},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.RTA.2011.235},
  URN =		{urn:nbn:de:0030-drops-31208},
  doi =		{10.4230/LIPIcs.RTA.2011.235},
  annote =	{Keywords: Complexity, DP Framework, Multiple Recursive Functions}
}
Document
Complexity Analysis of Term Rewriting Based on Matrix and Context Dependent Interpretations

Authors: Georg Moser, Andreas Schnabl, and Johannes Waldmann

Published in: LIPIcs, Volume 2, IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (2008)


Abstract
For a given (terminating) term rewriting system one can often estimate its \emph{derivational complexity} indirectly by looking at the proof method that established termination. In this spirit we investigate two instances of the interpretation method: \emph{matrix interpretations} and \emph{context dependent interpretations}. We introduce a subclass of matrix interpretations, denoted as \emph{triangular matrix interpretations}, which induce polynomial derivational complexity and establish tight correspondence results between a subclass of context dependent interpretations and restricted triangular matrix interpretations. The thus obtained new results are easy to implement and considerably extend the analytic power of existing results. We provide ample numerical data for assessing the viability of the method.

Cite as

Georg Moser, Andreas Schnabl, and Johannes Waldmann. Complexity Analysis of Term Rewriting Based on Matrix and Context Dependent Interpretations. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 2, pp. 304-315, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)


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@InProceedings{moser_et_al:LIPIcs.FSTTCS.2008.1762,
  author =	{Moser, Georg and Schnabl, Andreas and Waldmann, Johannes},
  title =	{{Complexity Analysis of Term Rewriting Based on  Matrix and Context Dependent Interpretations}},
  booktitle =	{IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
  pages =	{304--315},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-08-8},
  ISSN =	{1868-8969},
  year =	{2008},
  volume =	{2},
  editor =	{Hariharan, Ramesh and Mukund, Madhavan and Vinay, V},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2008.1762},
  URN =		{urn:nbn:de:0030-drops-17626},
  doi =		{10.4230/LIPIcs.FSTTCS.2008.1762},
  annote =	{Keywords: Term Rewriting, Derivational Complexity, Termination, Automation}
}
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