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Star-multiplicative graphs in pointed protomodular categories. (English) Zbl 1315.18013

Summary: Protomodularity, in the pointed case, is equivalent to the Split Short Five Lemma. It is also well known that this condition implies that every internal category is in fact an internal groupoid. In this work, this is condition (II) and we introduce two other conditions denoted (I) and (III). Under condition (I), every multiplicative graph is an internal category. Under condition (III), every star-multiplicative graph can be extended (uniquely) to a multiplicative graph, a problem raised by G. Janelidze in the semiabelian context.

MSC:

18D35 Structured objects in a category (MSC2010)