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Documents authored by Malbos, Philippe


Document
Homological Computations for Term Rewriting Systems

Authors: Philippe Malbos and Samuel Mimram

Published in: LIPIcs, Volume 52, 1st International Conference on Formal Structures for Computation and Deduction (FSCD 2016)


Abstract
An important problem in universal algebra consists in finding presentations of algebraic theories by generators and relations, which are as small as possible. Exhibiting lower bounds on the number of those generators and relations for a given theory is a difficult task because it a priori requires considering all possible sets of generators for a theory and no general method exists. In this article, we explain how homological computations can provide such lower bounds, in a systematic way, and show how to actually compute those in the case where a presentation of the theory by a convergent rewriting system is known. We also introduce the notion of coherent presentation of a theory in order to consider finer homotopical invariants. In some aspects, this work generalizes, to term rewriting systems, Squier's celebrated homological and homotopical invariants for string rewriting systems.

Cite as

Philippe Malbos and Samuel Mimram. Homological Computations for Term Rewriting Systems. In 1st International Conference on Formal Structures for Computation and Deduction (FSCD 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 52, pp. 27:1-27:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)


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@InProceedings{malbos_et_al:LIPIcs.FSCD.2016.27,
  author =	{Malbos, Philippe and Mimram, Samuel},
  title =	{{Homological Computations for Term Rewriting Systems}},
  booktitle =	{1st International Conference on Formal Structures for Computation and Deduction (FSCD 2016)},
  pages =	{27:1--27:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-010-1},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{52},
  editor =	{Kesner, Delia and Pientka, Brigitte},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2016.27},
  URN =		{urn:nbn:de:0030-drops-59821},
  doi =		{10.4230/LIPIcs.FSCD.2016.27},
  annote =	{Keywords: term rewriting system, Lawvere theory, Tietze equivalence, resolution, homology, convergent pres entation, coherent presentation}
}
Document
A Homotopical Completion Procedure with Applications to Coherence of Monoids

Authors: Yves Guiraud, Philippe Malbos, and Samuel Mimram

Published in: LIPIcs, Volume 21, 24th International Conference on Rewriting Techniques and Applications (RTA 2013)


Abstract
One of the most used algorithm in rewriting theory is the Knuth-Bendix completion procedure which starts from a terminating rewriting system and iteratively adds rules to it, trying to produce an equivalent convergent rewriting system. It is in particular used to study presentations of monoids, since normal forms of the rewriting system provide canonical representatives of words modulo the congruence generated by the rules. Here, we are interested in extending this procedure in order to retrieve information about the low-dimensional homotopy properties of a monoid. We therefore consider the notion of coherent presentation, which is a generalization of rewriting systems that keeps track of the cells generated by confluence diagrams. We extend the Knuth-Bendix completion procedure to this setting, resulting in a homotopical completion procedure. It is based on a generalization of Tietze transformations, which are operations that can be iteratively applied to relate any two presentations of the same monoid. We also explain how these transformations can be used to remove useless generators, rules, or confluence diagrams in a coherent presentation, thus leading to a homotopical reduction procedure. Finally, we apply these techniques to the study of some examples coming from representation theory, to compute minimal coherent presentations for them: braid, plactic and Chinese monoids.

Cite as

Yves Guiraud, Philippe Malbos, and Samuel Mimram. A Homotopical Completion Procedure with Applications to Coherence of Monoids. In 24th International Conference on Rewriting Techniques and Applications (RTA 2013). Leibniz International Proceedings in Informatics (LIPIcs), Volume 21, pp. 223-238, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2013)


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@InProceedings{guiraud_et_al:LIPIcs.RTA.2013.223,
  author =	{Guiraud, Yves and Malbos, Philippe and Mimram, Samuel},
  title =	{{A Homotopical Completion Procedure with Applications to Coherence of Monoids}},
  booktitle =	{24th International Conference on Rewriting Techniques and Applications (RTA 2013)},
  pages =	{223--238},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-53-8},
  ISSN =	{1868-8969},
  year =	{2013},
  volume =	{21},
  editor =	{van Raamsdonk, Femke},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.RTA.2013.223},
  URN =		{urn:nbn:de:0030-drops-40649},
  doi =		{10.4230/LIPIcs.RTA.2013.223},
  annote =	{Keywords: higher-dimensional rewriting, presentation of monoid, Knuth-Bendix completion, Tietze transformation, low-dimensional homotopy for monoids, coherence}
}
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