Homology of Small Categories
Homology of a small category with coefficients in a functor, the nerve and its geometric realisation, comparison with group homology, and the associated spectral sequences.
Every page in the KEVOS library tagged Satellites & Kan Extensions. 5 pages.
Homology of a small category with coefficients in a functor, the nerve and its geometric realisation, comparison with group homology, and the associated spectral sequences.
Left and right Kan extensions, their construction by colimits and limits, the adjunction characterisation, and their role in homology of small categories.
Projective classes, relative projectives, allowable epimorphisms, relative exactness, and the examples that motivate relative homological algebra.
Construction of relative derived functors from relative resolutions, their properties, the comparison with absolute derived functors, and worked examples.
Left and right satellites of an additive functor, their construction, the connection with derived functors, and their use when the category lacks enough projectives.