Derived functors as homotopy groups

Abstract

AbstractIn this paper a generalization of the interpretation of Robinson of torsion products as homotopy groups is given. This generalization allows us to define right derived functors of a coproduct preserving functor defined on a small category with all finite colimits to the category of abelian groups. We show that when the category is additive the definition coincides with the definitions of the right derived functors of Cartan and Eilenberg.