Homological algebra in pre-Abelian categories
- Cite this article as:
- Yakovlev, A.V. J Math Sci (1982) 19: 1060. doi:10.1007/BF01476122
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We construct derived functors in additive categories in which each morphism has a kernel, co-kernel, image, and coimage, but the image and coimage are not necessarily isomorphic. We prove that these derived functors possess the usual properties. The main difficulty is that the 3×3-lemma does not necessarily hold in the categories under consideration.