G-groupoids, crossed modules and the fun
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Ronald Brown; Christopher B Spencer
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Article
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1976
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Elsevier Science
β 427 KB
INTRODUUTION By a 8-groupoid is meant a group object in the category of groupoids. By a crossed m&.&. (A, B, b) is meant a pair A, B of groups together with an operation of the group B on the group A, and a morphism b: A + B of groups, satisfying: (i) b(a\*