New decidable upper bound of the second level in the Straubing-Therien concatenation hierarchy of star-free languages
2010 ◽
Vol Vol. 12 no. 4
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special issue dedicated to the second edition of the conference AutoMathA: from Mathematics to Applications International audience In a recent paper we gave a counterexample to a longstanding conjecture concerning the characterization of regular languages of level 2 in the Straubing-Therien concatenation hierarchy of star-free languages. In that paper a new upper bound for the corresponding pseudovariety of monoids was implicitly given. In this paper we show that it is decidable whether a given monoid belongs to the new upper bound. We also prove that this new upper bound is incomparable with the previous upper bound.
2012 ◽
Vol Vol. 13 no. 4
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Keyword(s):
2014 ◽
Vol Vol. 16 no. 2
(PRIMA 2013)
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Keyword(s):
2014 ◽
Vol Vol. 16 no. 2
(PRIMA 2013)
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Keyword(s):
2000 ◽
Vol 231
(1)
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pp. 5-15
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2010 ◽
Vol 76
(764)
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pp. 383-385
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