Results 21 to 30 of about 198 (35)

The finite basis problem for the monoid of 2 by 2 upper triangular tropical matrices

, 2016
For each positive $n$, let $u_n = v_n$ denote the identity obtained from the Adjan identity $(xy) (yx) (xy) (xy) (yx) = (xy) (yx) (yx) (xy) (yx)$ by substituting $(xy) \rightarrow (x_1 x_2 \dots x_n)$ and $(yx) \rightarrow (x_n \dots x_2 x_1)$.
Chen, Yuzhu, Hu, Xun, Luo, Yanfeng, Sapir, Olga   +3 more
core   +1 more source

Tameness of pseudovariety joins involving R [PDF]

, 2004
2000 Mathematics Subject Classification: 20M07 (primary); 20M05, 20M35, 68Q70 (secondary).In this paper, we establish several decidability results for pseudovariety joins of the form VvW, where V is a subpseudovariety of J or the pseudovariety R.
B Herwig, B Steinberg, CJ Ash, D Albert, J Almeida, J Almeida, J Almeida, J Almeida, J Almeida, J Almeida, J Almeida, J Almeida, J Almeida, J Almeida, J Almeida, J Almeida, J Almeida, J Rhodes, J-E Pin, JC Costa, JC Costa, Jorge Almeida, José Carlos Costa, K Auinger, M Zeitoun, Marc Zeitoun, Th Coulbois   +26 more
core   +4 more sources

Cancellable elements of the lattices of varieties of semigroups and epigroups [PDF]

, 2019
We completely determine all semigroup [epigroup] varieties that are cancellable elements of the lattice of all semigroup [respectively epigroup] varieties.Comment: 17 pages, 3 figures. Compared with the previous version, we add Corollary 1.4 and Figure
Shaprynskii, V. Yu., Skokov, D. V., Vernikov, B. M.   +2 more
core   +1 more source

Monoid varieties with extreme properties

, 2018
Finite monoids that generate monoid varieties with uncountably many subvarieties seem rare, and surprisingly, no finite monoid is known to generate a monoid variety with countably infinitely many subvarieties.
Jackson, Marcel, Lee, Edmond W. H.
core   +1 more source

Modular and lower-modular elements of lattices of semigroup varieties [PDF]

, 2010
The paper contains three main results. First, we show that if a commutative semigroup variety is a modular element of the lattice Com of all commutative semigroup varieties then it is either the variety COM of all commutative semigroups or a nil-variety ...
L. N. Shevrin, V. Yu. Shaprynskǐi
core  

Finite semigroups that are minimal for not being Malcev nilpotent

, 2014
We give a description of finite semigroups $S$ that are minimal for not being Malcev nilpotent, i.e. every proper subsemigroup and every proper Rees factor semigroup is Malcev nilpotent but $S$ is not.
Jespers, E., Shahzamanian, M. H.
core   +1 more source

Rees quotients of numerical semigroups

, 2012
We introduce a class of finite semigroups obtained by considering Rees quotients of numerical semigroups. Several natural questions concerning this class, as well as particular subclasses obtained by considering some special ideals, are answered while ...
Delgado, Manuel, Fernandes, Vítor H.
core   +1 more source

A description of a class of finite semigroups that are near to being Malcev nilpotent

, 2012
In this paper we continue the investigations on the algebraic structure of a finite semigroup $S$ that is determined by its associated upper non-nilpotent graph $\mathcal{N}_{S}$.
E. JESPERS, M. H. SHAHZAMANIAN, Mal'cev A. I., Okninski J.   +3 more
core   +1 more source

Lower-modular elements of the lattice of semigroup varieties. III

, 2010
We completely determine all lower-modular elements of the lattice of all semigroup varieties. As a corollary, we show that a lower-modular element of this lattice is modular.Comment: 10 pages, 1 ...
Shaprynskii, V. Yu., Vernikov, B. M.
core  

M-Solid Subvarieties of some Varieties of Commutative Semigroups [PDF]

, 1997
∗ The research of the author was supported by the Alexander v. Humboldt-Stiftung.The basic concepts are M -hyperidentities, where M is a monoid of hypersubstitutions.
Koppitz, J.
core