Cofibrations. II: Left exact right actions and compositions of gamuts (Q1068181)

This paper continues the study of cofibrations in the bicategory Top of topoi and geometric morphisms [ibid. 32, 71-94 (1984; Zbl 0535.18006)]. The two geometric morphisms involved in a cofibration are examined and the right module action is interpreted as ''disjoint universal sums'' in the sense of indexed categories [Indexed categories and their applications, Lect. Notes Math. 661 (1978; Zbl 0372.00009)]. Composition of cofibrations is interpreted as that of gamuts; composition of codiscrete cofibrations is just composition of left-exact functors.