English

Normal category of partitions of a set

Group Theory 2017-01-24 v2 Rings and Algebras

Abstract

Let TXT_X be the semigroup of all non-invertible transformations on an arbitrary set XX. It is known that TXT_X is a regular semigroup. The principal right(left) ideals of a regular semigroup SS with partial left(right) translations as morphisms form a normal category R(S)\mathcal{R}( S )(L(S)\mathcal{L}( S )). Here we consider the category Π(X)\Pi(X) of partitions of a set XX and show that it admits a normal category structure and that Π(X)\Pi(X) is isomorphic to the category R(TX)\mathcal{R}( T_X ). We also consider the normal dual NP(X)N^\ast \mathscr{P}(X) of the power-set category P(X)\mathscr{P}(X) associated with XX and show that NP(X)N^\ast \mathscr{P}(X) is isomorphic to the partition category - Π(X)\Pi(X) of the set XX.

Keywords

Cite

@article{arxiv.1509.02888,
  title  = {Normal category of partitions of a set},
  author = {A. R. Rajan and Azeef Muhammed P A},
  journal= {arXiv preprint arXiv:1509.02888},
  year   = {2017}
}