On a subclass of context-free groups
On autogenerating systems
On certain codes admitting inverse semigroups as syntactic monoids.
On closure operators on monoids
On commutative Kleene monoids.
On free inverse monoid languages
On graph products of automatic monoids
The graph product is an operator mixing direct and free products. It is already known that free products and direct products of automatic monoids are automatic. The main aim of this paper is to prove that graph products of automatic monoids of finite geometric type are still automatic. A similar result for prefix-automatic monoids is established.
On graph products of automatic monoids
The graph product is an operator mixing direct and free products. It is already known that free products and direct products of automatic monoids are automatic. The main aim of this paper is to prove that graph products of automatic monoids of finite geometric type are still automatic. A similar result for prefix-automatic monoids is established.
On ideal extensions of completely simple semigroups.
On infinitary finite length codes
On one definition of grammatical categories
On optimal factorization of free semigroups into free subsemigroups.
On recognition and compactification.
On right congruences associated with the input semigroup S of automata.
On semisimple bands.
On some properties of the syntactic semigroup of a very pure subsemigroup
On some subsemigroups of a free semigroup.
On syntacticity of finite regular semigroups.
On the decidability of semigroup freeness∗
This paper deals with the decidability of semigroup freeness. More precisely, the freeness problem over a semigroup S is defined as: given a finite subset X ⊆ S, decide whether each element of S has at most one factorization over X. To date, the decidabilities of the following two freeness problems have been closely examined. In 1953, Sardinas and Patterson proposed a now famous algorithm for the freeness problem over the free monoids....
On the decidability of semigroup freeness
This paper deals with the decidability of semigroup freeness. More precisely, the freeness problem over a semigroup S is defined as: given a finite subset X ⊆ S, decide whether each element of S has at most one factorization over X. To date, the decidabilities of the following two freeness problems have been closely examined. In 1953, Sardinas and Patterson proposed a now famous algorithm for the freeness problem over the free monoids. In 1991, Klarner, Birget and Satterfield proved the undecidability...