In my diploma thesis, I did some work on finitely presented semigroups.
As I've implemented my functions in GAP, I would be highly interested in
whether there's already some semigroup stuff floating around and if so,
My work in short: A semigroup given by a presentation or its operation
table can be checked for subsemigroups, group kernel, endomorphisms, etc....
The functions however do not yet comply 100% with the format used in the GAP
libraries. I plan to remedy that situation within the next four weeks.