Dual to projective resolution: an exact sequence 0 → M → I⁰ → I¹ → ⋯ with each I^k injective. Every object in an abelian category with enough injectives has one. Used to define right-derived functors (e.g. Ext via Hom(-, I•), sheaf…
Dual to projective resolution: an exact sequence 0 → M → I⁰ → I¹ → ⋯ with each I^k injective. Every object in an abelian category with enough injectives has one. Used to define right-derived functors (e.g. Ext via Hom(-, I•), sheaf…