Regular solutions of language inequalities and well quasi-orders

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Authors	KUNC Michal
Year of publication	2005
Type	Article in Periodical
Magazine / Source	Theoretical Computer Science
MU Faculty or unit	Faculty of Science
Citation
Web	http://dx.doi.org/10.1016/j.tcs.2005.09.018
Field	General mathematics
Keywords	Language equation; Regular language; Well quasi-order; Syntactic semigroup; Finite simple semigroup
Description	By means of constructing suitable well quasi-orders of free monoids we prove that all maximal solutions of certain systems of language inequalities are regular. This way we deal with a wide class of systems of inequalities where all constants are languages recognized by finite simple semigroups. In a similar manner we also demonstrate that the largest solution of the inequality XK subset LX is regular provided the language L is regular.
Related projects:	Mathematical structures of algebra and geometry