Theorems · Theorem · group theory

AddSubgroup.index_map_eq

∀ {G : Type u_1} {G' : Type u_2} [inst : AddGroup G] [inst_1 : AddGroup G'] (H : AddSubgroup G) {f : G →+ G'},
  Function.Surjective ⇑f → f.ker ≤ H → (AddSubgroup.map f H).index = H.index

Defined in

Mathlib.GroupTheory.Index

Cited by

1 results in Mathlib

Foundations

Depth 98 from the axioms · uses propext, Classical.choice, Quot.sound

Assumes

AddGroupAddGroup