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Squares of regular languages
Author(s) -
Lischke Gerhard
Publication year - 2005
Publication title -
mathematical logic quarterly
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.473
H-Index - 28
eISSN - 1521-3870
pISSN - 0942-5616
DOI - 10.1002/malq.200410032
Subject(s) - square (algebra) , decidability , mathematics , context (archaeology) , set (abstract data type) , regular language , context free language , combinatorics , linguistics , discrete mathematics , computer science , natural language processing , programming language , artificial intelligence , rule based machine translation , automaton , geometry , philosophy , history , archaeology
The square of a language L is the set of all words pp where p ∈ L . The square of a regular language may be regular too or context‐free or none of both. We give characterizations for each of these cases and show that it is decidable whether a regular language has one of these properties. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)