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The Boolean Hierarchy over Level 1/2 of the Straubing-Therien Hierarchy
[article]

1998
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arXiv
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pre-print

For some fixed alphabet A, a language L of A* is in the class L(1/2) of the Straubing-Therien hierarchy if and only if it can be expressed as a finite union of languages A*aA*bA*...A*cA*, where a,b,...,c are letters. The class L(1) is defined as the boolean closure of L(1/2). It is known that the classes L(1/2) and L(1) are decidable. We give a membership criterion for the single classes of the boolean hierarchy over L(1/2). From this criterion we can conclude that this boolean hierarchy is

arXiv:cs/9809118v1
fatcat:gez5cgx7efgjhevgwqthywniq4