English
The inverse of a congruence is the congruence of the inverses: congr(f.symm, g.symm) equals (congr(f,g)).symm.
Русский
Обратный конгруэнции соответствует конгруэнции обратных изоморфизмов: congr(f.symm, g.symm) = (congr(f,g)).symm.
LaTeX
$$congr(f.symm, g.symm) = (congr(f, g)).symm$$
Lean4
theorem congr_trans (f₁ : A ≃ₐ[S] C) (f₂ : C ≃ₐ[S] E) (g₁ : B ≃ₐ[R] D) (g₂ : D ≃ₐ[R] F) :
congr (f₁.trans f₂) (g₁.trans g₂) = (congr f₁ g₁).trans (congr f₂ g₂) :=
AlgEquiv.coe_algHom_injective <| map_comp f₂.toAlgHom f₁.toAlgHom g₂.toAlgHom g₁.toAlgHom