Bad News on Decision Problems for Patterns

Authors:
Dominik D. Freydenberger;Daniel Reidenbach
Affiliations:
Institut für Informatik, Goethe-Universität, Frankfurt am Main, Germany D-60054;Department of Computer Science, Loughborough University, Loughborough, United Kingdom LE11 3TU
Venue:
DLT '08 Proceedings of the 12th international conference on Developments in Language Theory
Year:
2008

Citing 13
Cited 0

Decision problems for patterns

Journal of Computer and System Sciences
A note on the equivalence problem of E-patterns

Information Processing Letters
Handbook of formal languages, vol. 1: word, language, grammar

Handbook of formal languages, vol. 1: word, language, grammar
On the equivalence problem for E-pattern languages

Theoretical Computer Science
Reversal-Bounded Multicounter Machines and Their Decision Problems

Journal of the ACM (JACM)
The expressibility of languages and relations by word equations

Journal of the ACM (JACM)
Polynomial Time Inference of Extended Regular Pattern Languages

Proceedings of RIMS Symposium on Software Science and Engineering
The Relation of Two Patterns with Comparable Languages

STACS '88 Proceedings of the 5th Annual Symposium on Theoretical Aspects of Computer Science
A non-learnable class of E-pattern languages

Theoretical Computer Science - Algorithmic learning theory(ALT 2002)
Discontinuities in pattern inference

Theoretical Computer Science
Developments from enquiries into the learnability of the pattern languages from positive data

Theoretical Computer Science
An examination of Ohlebusch and Ukkonen's conjecture on the equivalence problem for E-pattern languages

Journal of Automata, Languages and Combinatorics
Compute inclusion depth of a pattern

COLT'05 Proceedings of the 18th annual conference on Learning Theory

Quantified Score

Hi-index	0.00

Visualization

Abstract

We study the inclusion problem for pattern languages, which is shown to be undecidable by Jiang et al. (J. Comput. System Sci. 50, 1995). More precisely, Jiang et al. demonstrate that there is no effective procedure deciding the inclusion for the class of allpattern languages over allalphabets. Most applications of pattern languages, however, consider classes over fixedalphabets, and therefore it is practically more relevant to ask for the existence of alphabet-specificdecision procedures. Our first main result states that, for all but very particular cases, this version of the inclusion problem is also undecidable. The second main part of our paper disproves the prevalent conjecture on the inclusion of so-called similar E-pattern languages, and it explains the devastating consequences of this result for the intensive previous research on the most prominent open decision problem for pattern languages, namely the equivalence problem for general E-pattern languages.