On Croisot - languages and Dubreil - languages having a group as syntactic monoid.

Iranian Languages as Gardens

Factorizations in the Monoid of Languages

Solutions of equations AB = BA, AL = LB and LA = LB of languages are investigated. Properties concerning some relations defined on languages which satisfy equations AB = BA, AL = LB or LA = LB are studied. Some results are

First-Order Quantifiers and the Syntactic Monoid of Height Fragments of Picture Languages

We investigate the expressive power of first-order quantifications in the context of monadic second-order logic over pictures. We show that k+1 set quantifier alternations allow to define a picture language that cannot be defined using k set quantifier alternations preceded by arbitrarily many first-order quantifier alternations. The approach uses, for a given picture language L and an integer ...

Monoid Automata for Displacement Context-Free Languages

In 2007 Kambites presented an algebraic interpretation of Chomsky-Schützenberger theorem for context-free languages. We give an interpretation of the corresponding theorem for the class of displacement context-free languages which are equivalent to well-nested multiple context-free languages. We also obtain a characterization of kdisplacement context-free languages in terms of monoid automata a...

On Beta-Shifts Having Arithmetical Languages

Let β be a real number with 1 < β < 2. We prove that the language of the β-shift is ∆n iff β is a ∆n-real. The special case where n is 1 is the independently interesting result that the language of the β-shift is decidable iff β is a computable real. The “if” part of the proof is non-constructive; we show that for Walters’ version of the β-shift, no constructive proof exists.