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Let C be a finite category. For an object X of C one has the hom-functor Hom(-,X) of C to Set. If G is a subgroup of Aut(X), one has the quotient functor Hom(-,X)/G. We show that any finite product of hom-functors of C is a sum of hom-functors if and only if C has pushouts and coequalizers and that any finite product of hom-functors of C is a sum of functors of the form \Hom(-,X)/G if and only if C has pushouts. These are variations of the fact that a finite category has products if and only if it has coproducts.
@article{TAC_2015_30_a29, author = {D. Tambara}, title = {Finite categories with pushouts}, journal = {Theory and applications of categories}, pages = {1017--1031}, publisher = {mathdoc}, volume = {30}, year = {2015}, language = {en}, url = {http://geodesic.mathdoc.fr/item/TAC_2015_30_a29/} }
D. Tambara. Finite categories with pushouts. Theory and applications of categories, Tome 30 (2015), pp. 1017-1031. http://geodesic.mathdoc.fr/item/TAC_2015_30_a29/