simp only [Prod.map, toFun_inv_toFun, implies_true]
case refine_1
n : Nat
x y : Permutation n
⊢ ∀ (b : Fin n × Fin n), Prod.map (toFun (inv y)) (toFun (inv y)) (Prod.map (toFun y) (toFun y) b) = b
no goals