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> ^ Subject:

Hello. I have just acquired GAP, and apologize if

this question has been dealt with previously.

I need to compute structures on semigroups of

partial 1-1 functions, e.g., Green's relations.

GAP does not seem to have any of the relevant

things I need for this. Has anyone implemented

anything that would help, such as partial

functions?

If not, I'd like some feedback on my initial

ideas for implementing this. At first reading,

it appears that partial functions should be

implemented as lists with holes, and a new

domain type, something like "semigroups of

partial 1-1 functions" needs to be constructed

as a set of these lists, together with

operations that compose partial functions,

compute Green's relations, etc. I'll need to

build several new domains, such as "Brandt

semigroups" and "inverse semigroups".

Once the semigroup stuff is implemented, then

I can take advantage of GAP's group-theoretic

abilities, as I am computing symmetries of

various structures in Green's relations.

Thanks in advance,

Paul Benjamin

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