The two-sided Karnofsky-Rhodes expansion of a semigroup
 
 
Description:  In semigroup theory, the term "expansion" refers to an endofunctor in the category of semigroups, equipped with a natural transformation to the identity functor which is surjective in each object.

There is a big number of expansions with names of semigroup theorists, a reflection of their great usefulness to address problems in the field. Examples are the Rhodes expansion, the Birget-Rhodes expansion, the Szendrei expansion, the McCammond expansion, the Pin-Thérien expansion, the Henckell-Schutzenberger expansion, the Karnofsky-Rhodes expansion. In this talk we look more closely to a variant of the latter, the two-sided Karnofsky-Rhodes expansion. This expansion is associated with the property of a semigroup being equidivisible, as shown in joint work with Almeida. (A semigroup is said to be equidivisible when two distinct factorizations of an arbitrary element have a common refinement.)

Date:  2022-01-24
Start Time:   15:00
Speaker:  Alfredo Costa (CMUC, Univ. Coimbra)
Institution:  CMUC, University of Coimbra
Place:  Sala Pedro Nunes, DMUC
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