License: Creative Commons Attribution 3.0 Unported license (CC BY 3.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.STACS.2018.48
URN: urn:nbn:de:0030-drops-84828
URL: http://dagstuhl.sunsite.rwth-aachen.de/volltexte/2018/8482/
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Luttenberger, Michael ; Palenta, Raphaela ; Seidl, Helmut

Computing the Longest Common Prefix of a Context-free Language in Polynomial Time

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Abstract

We present two structural results concerning the longest common prefixes of non-empty languages.
First, we show that the longest common prefix of the language generated by a context-free grammar of size N
equals the longest common prefix of the same grammar where the heights of the derivation trees are bounded by
4N.
Second, we show that each non-empty language L has a representative subset of at most three elements which behaves
like L w.r.t. the longest common prefix as well as w.r.t. longest common prefixes of L after unions or
concatenations with arbitrary other languages.
From that, we conclude
that the longest common prefix, and thus the longest common suffix, of a context-free language can be computed in polynomial time.

BibTeX - Entry

@InProceedings{luttenberger_et_al:LIPIcs:2018:8482,
  author =	{Michael Luttenberger and Raphaela Palenta and Helmut Seidl},
  title =	{{Computing the Longest Common Prefix of a Context-free Language in Polynomial Time}},
  booktitle =	{35th Symposium on Theoretical Aspects of Computer Science (STACS 2018)},
  pages =	{48:1--48:13},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-062-0},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{96},
  editor =	{Rolf Niedermeier and Brigitte Vall{\'e}e},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{http://drops.dagstuhl.de/opus/volltexte/2018/8482},
  URN =		{urn:nbn:de:0030-drops-84828},
  doi =		{10.4230/LIPIcs.STACS.2018.48},
  annote =	{Keywords: longest common prefix, context-free languages, combinatorics on words}
}

Keywords: longest common prefix, context-free languages, combinatorics on words
Collection: 35th Symposium on Theoretical Aspects of Computer Science (STACS 2018)
Issue Date: 2018
Date of publication: 27.02.2018

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