2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/71760Classical homological algebra takes place in additive categories. In homotopy theory such additive categories arise as homotopy categories of ``additive groupoid enriched categories'', in which a secondary analog of homological algebra can be performed. We introduce secondary chain complexes and secondary resolutions leading to the concept of secondary derived functors. As a main result we show that the E_3-term of the Adams spectral sequence can be expressed as a secondary derived functor. This result can be used to compute the E_3-term explicitly by an algorithm.Reference to math.AT/0407045 addedAlgebraic TopologyCategory TheoryK-Theory and Homology18G10, 55T15, 55S20 (Primary) 55U99, 18D05, 18G25, 18G40 (Secondary)text