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We give several reformulations of action representability of a category as well as action representability of its category of morphisms. In particular we show that for a semi-abelian category C, its category of morphisms is action representable if and only if the functor from the category of split extensions in C to C, sending a split extension to its kernel, is a prefibration. To obtain these reformulations we show that certain conditions are equivalent for right regular spans of categories.
@article{TAC_2017_32_a42, author = {J. R. A. Gray}, title = {Action representability via spans and prefibrations}, journal = {Theory and applications of categories}, pages = {1501--1521}, publisher = {mathdoc}, volume = {32}, year = {2017}, language = {en}, url = {http://geodesic.mathdoc.fr/item/TAC_2017_32_a42/} }
J. R. A. Gray. Action representability via spans and prefibrations. Theory and applications of categories, Tome 32 (2017), pp. 1501-1521. http://geodesic.mathdoc.fr/item/TAC_2017_32_a42/