The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

Displaying similar documents to “Undecidable varieties with solvable word problems. III (a semigroup variety).”

Finite basis problem for 2-testable monoids

Edmond Lee (2011)

Open Mathematics

Similarity:

A monoid S 1 obtained by adjoining a unit element to a 2-testable semigroup S is said to be 2-testable. It is shown that a 2-testable monoid S 1 is either inherently non-finitely based or hereditarily finitely based, depending on whether or not the variety generated by the semigroup S contains the Brandt semigroup of order five. Consequently, it is decidable in quadratic time if a finite 2-testable monoid is finitely based.

Presolid varieties of n-semigroups

Avapa Chantasartrassmee, Jörg Koppitz (2005)

Discussiones Mathematicae - General Algebra and Applications

Similarity:

he class of all M-solid varieties of a given type t forms a complete sublattice of the lattice ℒ(τ) of all varieties of algebrasof type t. This gives a tool for a better description of the lattice ℒ(τ) by characterization of complete sublattices. In particular, this was done for varieties of semigroups by L. Polák ([10]) as well as by Denecke and Koppitz ([4], [5]). Denecke and Hounnon characterized M-solid varieties of semirings ([3]) and M-solid varieties of groups were characterized...