UNDERLYING GRUPOIDS

In this paper we describe a package XMOD (Wensley andAlp,1993) of functions for computing with crossed modules, theirmorphisms and derivations; cat' -groups, their morphisms andsections, written using the sf GAP (Schonert , 1993) group theoryprogramming language. We have also enumerated the isomorphismclasses of cat-groups in (Alp ,1997) and (Alp, Wensley ,1997) and(Alp ,1997) We gave the application algorithms and somemathematical results on cat' -group structures in (Alp, 1998) . We alsomade a computational comment on pre-crossed modules, pre-cat Igroupsand underlying grupoids in this paper.

Anahtar Kelimeler:

Crossed modules, Cat'<groups, underlying grupoids

NDERL YING GRUPOIDS

In this paper we describe a package XMOD (Wensley and Alp,1993) of functions for computing with crossed modules, their morphisms and derivations; cat' -groups, their morphisms and sections, written using the sf GAP (Schonert , 1993) group theory programming language. We have also enumerated the isomorphism classes of cat-groups in (Alp ,1997) and (Alp, Wensley ,1997) and (Alp ,1997) We gave the application algorithms and some mathematical results on cat' -group structures in (Alp, 1998) . We also made a computational comment on pre-crossed modules, pre-cat Igroups and underlying grupoids in this paper.

Keywords:

Crossed modules, Cat'<groups, underlying grupoids,

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