The left restriction semigroups have arisen in a number of contexts, one being as the abstract characterization of semigroups of partial maps, another as the ‘weakly left E-ample’ semigroups of the ‘York school’, and, more recently as a variety of unary semigroups defined by a set of simple identities. We initiate a study of the lattice of varieties of such semigroups and, in parallel, of their...

Convolution semigroups of states on a quantum group form the natural noncommutative analogue of convolution semigroups of probability measures on a locally compact group. Here we initiate a theory of weakly continuous convolution semigroups of functionals on a C∗bialgebra, the noncommutative counterpart of locally compact semigroup. On locally compact quantum groups we obtain a bijective corres...

We investigate the class of numerical semigroups verifying the property ρ i+1 − ρ i ≥ 2 for every two consecutive elements smaller than the conductor. These semigroups generalize Arf semigroups.

We study the semigroups isomorphic to principal ideals of finitely generated commutative monoids. We define the concept of finite presentation for this kind of semigroups. Furthermore, we show how to obtain information on these semigroups from their presentations.

The aim of this paper is to investigate links of the recently introduced B-bounded semigroups [5] with other generalizations of semigroups, like C -regularized semigroups and C -existence families.

in this paper we have generalized the concepts of ,q-fuzzy ideals, ,q-fuzzy quasi-ideals and,q-fuzzy bi-ideals by introducing the concepts of   k ,q -fuzzy ideals,   k ,q -fuzzy quasiideals and   k ,q -fuzzy bi-ideals in ternary semigroups and several related properties are investigated. different characterizations of regular and weakly regular ternary semigroups b...

We consider the question of membership of A ∨ G, where A and G are the pseudovarieties of finite aperiodic semigroups, and finite groups, respectively. We find a straightforward criterion for a semigroup S lying in a class of finite semigroups that are weakly abundant, to be in A ∨ G. The class of weakly abundant semigroups contains the class of regular semigroups, but is much more extensive; w...

A proportionally modular numerical semigroup is the set of nonnegative integer solutions to a Diophantine inequality of the type axmod b ≤ cx . We give a new presentation for these semigroups and we relate them with a type of affine full semigroups. Next, we describe explicitly the minimal generating system for the affine full semigroups we are considering. As a consequence, we obtain generatin...

We consider the two-player game chomp on posets associated to numerical semigroups and show that the analysis of strategies for chomp is strongly related to classical properties of semigroups. We characterize which player has a winning-strategy for symmetric semigroups, semigroups of maximal embedding dimension and several families of numerical semigroups generated by arithmetic sequences. Furt...

We first give some useful characterizations of regular semigroups and right weakly regular semigroups by the properties of their bi-ideals, interior ideals, left ideals and right ideals. Based on these characterizations, we also characterize regular semigroups and right weakly regular semigroups by the properties of their (∈,∈ ∨qk)-fuzzy (generalized) bi-ideals, (∈,∈ ∨qk)-fuzzy interior ideals,...