The paper generalizes the notion of a congruence on a category and pursues some of its applications. In particular, generalized congruences are used to provide a concrete construction of coequalizers in ${\cal C}at$. Extremal, regular and various other classes of epimorphic functors are characterized and inter-related.
Keywords: congruence, epimorphic functor, coequalizer, category of small categories.
1991 MSC: 18A05, 18A20, 18A30, 18A32, 18B99.
Theory and Applications of Categories, Vol. 5, 1999, No. 11, pp 266-280.
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