2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/218787We define Anderson-Brown-Cisinski (ABC) cofibration categories, and construct homotopy colimits of diagrams of objects in ABC cofibration categories. Homotopy colimits for Quillen model categories are obtained as a particular case. We attach to each ABC cofibration category a left Heller derivator. A dual theory is developed for homotopy limits in ABC fibration categories and for right Heller derivators. These constructions provide a natural framework for 'doing homotopy theory' in ABC (co)fibration categories.Ams-latex, 158 pages. Corrections to Thm. 6.4.1 and Def. 7.2.5Algebraic TopologyK-Theory and Homology18G55, 55U35, 18G10, 18G30, 55U10text