English
If I and J are two-sided ideals with I = J in a ring R, then R/I is ring-isomorphic to R/J.
Русский
Пусть I и J — двусторонние идеалы кольца R и I = J. Тогда R/I и R/J изоморфны как кольца.
LaTeX
$$$$R/I \cong R/J \quad\text{whenever}\quad I = J,$$$$
Lean4
/-- Quotienting by equal ideals gives equivalent rings.
See also `Submodule.quotEquivOfEq` and `Ideal.quotientEquivAlgOfEq`.
-/
def quotEquivOfEq (h : I = J) : R ⧸ I ≃+* R ⧸ J :=
{ Submodule.quotEquivOfEq I J h with
map_mul' := by
rintro ⟨x⟩ ⟨y⟩
rfl }