On free commutative groupoids.
On free products of bands.
On free products of bicyclic monoids.
On generating regular elements in the semigroup of binary relations.
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 low-complexity bi-infinite words and their factors
In this paper we study bi-infinite words on two letters. We say that such a word has stiffness if the number of different subwords of length equals for all sufficiently large. The word is called -balanced if the numbers of occurrences of the symbol a in any two subwords of the same length differ by at most . In the present paper we give a complete description of the class of bi-infinite words of stiffness and show that the number of subwords of length from this class has growth order...
On optimal factorization of free semigroups into free subsemigroups.
On permutation properties in groups and semigroups.
On presentations of Brauer-type monoids
We obtain presentations for the Brauer monoid, the partial analogue of the Brauer monoid, and for the greatest factorizable inverse submonoid of the dual symmetric inverse monoid. In all three cases we apply the same approach, based on the realization of all these monoids as Brauer-type monoids.
On principal ideals of triply-generated telescopic semigroups.
On -commutativity of -permutable semigroups.
On rich monoids
On semidirect and two-sided semidirect products of finite trivial monoids
On semigroups admitting ring structure.
On semigroups admitting ring structure III
On Semigroups Defined by the Identity xxy = y
On semigroups with least generating sets.
On some finiteness conditions in semigroup and group theory.
On some free semigroups, generated by matrices
Let We call a complex number “semigroup free“ if the semigroup generated by and is free and “free” if the group generated by and is free. First families of semigroup free ’s were described by J. L. Brenner, A. Charnow (1978). In this paper we enlarge the set of known semigroup free ’s. To do it, we use a new version of “Ping-Pong Lemma” for semigroups embeddable in groups. At the end we present most of the known results related to semigroup free and free numbers in a common picture....