Pushouts of Categories,Derived Limits,and Colimits |
| |
| Authors: | Lukáš Vokřínek |
| |
| Institution: | 1. Department of Mathematics and Statistics, Masaryk University, Brno, Czech Republickoren@math.muni.cz |
| |
| Abstract: | We provide a counterexample to a theorem of Ford, namely a pushout square of categories with all involved functors injective, such that there is no associated exact “Mayer–Vietoris” sequence of derived limits. Further, we construct a Mayer–Vietoris sequence for derived (co)limits under some additional hypotheses, extending the well-known case of a pushout square of group monomorphisms. |
| |
| Keywords: | Derived limit Derived colimit Mayer–Vietoris sequence Pushout of categories |
|
|
