Three Approaches to Inverse Semigroups
Christopher Hollings · European Journal of Pure and Applied Mathematics · 2015
I give a historical survey of the three main approaches to the study of the structure of inverse semigroups. The first is that via inductive groupoids, as studied by Charles Ehresmann. The second concerns the notion of a fundamental inverse semigroup and its Munn representation. Finally, the third centres upon the concept of an E-unitary or proper inverse semigroup and its representation (due to McAlister) by a so-called P-semigroup.