English
Restating the inverse equivalence: it is the inverse of the main equivalence between Mat R and Mat_(SingleObj (R^op)).
Русский
Повторное определение обратной эквивалентности: это обратная эквивалентность между Mat R и Mat_(SingleObj (R^op)).
LaTeX
$$$\mathrm{equivalenceSingleObjInverse}(R)$ is defined as the inverse of $\mathrm{equivalenceSingleObj}(R)$$$
Lean4
/-- Auxiliary definition for `CategoryTheory.Mat.equivalenceSingleObj`. -/
@[simps]
def equivalenceSingleObjInverse : Mat_ (SingleObj Rᵐᵒᵖ) ⥤ Mat R
where
obj X := FintypeCat.of X.ι
map f i j := MulOpposite.unop (f i j)
map_id
X := by
ext
simp only [Mat_.id_def, id_def]
split_ifs <;> rfl
map_comp f
g := by
-- Porting note: this proof was automatic in mathlib3
ext
simp only [Mat_.comp_apply, comp_apply]
apply Finset.unop_sum