-- Module: Mathlib.CategoryTheory.Action.Concrete
Goal:
G : Type u_1
inst : Group G
H N : Subgroup G
inst_1 : Fintype (G ⧸ N)
inst_2 : N.Normal
x : G ⧸ N
h :
  ∀ (a : G),
    Eq (α := (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (V (ofMulAction G (FintypeCat.of (G ⧸ N)))))
      ((@ConcreteCategory.hom _ (ObjectProperty.FullSubcategory.category Finite)
              (fun (X Y : ObjectProperty.FullSubcategory Finite) ↦ TypeCat.Fun X.obj Y.obj)
              (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj)
              (fun (X Y : ObjectProperty.FullSubcategory Finite) ↦
                (TypeCat.instFunLikeFun : FunLike (TypeCat.Fun X.obj Y.obj) X.obj Y.obj))
              _ _ _
              (Hom.hom { hom := FintypeCat.homMk (Quotient.lift (fun (σ : G) ↦ ⟦σ * 1⁻¹⟧) ⋯), comm := ⋯ } :
                V (ofMulAction G (FintypeCat.of (G ⧸ N))) ⟶ V (ofMulAction G (FintypeCat.of (G ⧸ N)))) :
            (a : (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (ofMulAction G (FintypeCat.of (G ⧸ N))).V) →
              (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (ofMulAction G (FintypeCat.of (G ⧸ N))).V)
          ⟦a⟧ :
        (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (V (ofMulAction G (FintypeCat.of (G ⧸ N)))))
      ((@ConcreteCategory.hom _ (ObjectProperty.FullSubcategory.category Finite)
              (fun (X Y : ObjectProperty.FullSubcategory Finite) ↦ TypeCat.Fun X.obj Y.obj)
              (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj)
              (fun (X Y : ObjectProperty.FullSubcategory Finite) ↦
                (TypeCat.instFunLikeFun : FunLike (TypeCat.Fun X.obj Y.obj) X.obj Y.obj))
              _ _ _
              (Hom.hom 1 : V (ofMulAction G (FintypeCat.of (G ⧸ N))) ⟶ V (ofMulAction G (FintypeCat.of (G ⧸ N)))) :
            (a : (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (ofMulAction G (FintypeCat.of (G ⧸ N))).V) →
              (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (ofMulAction G (FintypeCat.of (G ⧸ N))).V)
          ⟦a⟧ :
        (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (V (ofMulAction G (FintypeCat.of (G ⧸ N)))))
⊢ Eq (α := (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (V (ofMulAction G (FintypeCat.of (G ⧸ N)))))
    ((@ConcreteCategory.hom _ (ObjectProperty.FullSubcategory.category Finite)
            (fun (X Y : ObjectProperty.FullSubcategory Finite) ↦ TypeCat.Fun X.obj Y.obj)
            (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj)
            (fun (X Y : ObjectProperty.FullSubcategory Finite) ↦
              (TypeCat.instFunLikeFun : FunLike (TypeCat.Fun X.obj Y.obj) X.obj Y.obj))
            _ _ _
            (Hom.hom { hom := FintypeCat.homMk (Quotient.lift (fun (σ : G) ↦ ⟦σ * 1⁻¹⟧) ⋯), comm := ⋯ } :
              V (ofMulAction G (FintypeCat.of (G ⧸ N))) ⟶ V (ofMulAction G (FintypeCat.of (G ⧸ N)))) :
          (a : (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (ofMulAction G (FintypeCat.of (G ⧸ N))).V) →
            (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (ofMulAction G (FintypeCat.of (G ⧸ N))).V)
        x :
      (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (V (ofMulAction G (FintypeCat.of (G ⧸ N)))))
    ((@ConcreteCategory.hom _ (ObjectProperty.FullSubcategory.category Finite)
            (fun (X Y : ObjectProperty.FullSubcategory Finite) ↦ TypeCat.Fun X.obj Y.obj)
            (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj)
            (fun (X Y : ObjectProperty.FullSubcategory Finite) ↦
              (TypeCat.instFunLikeFun : FunLike (TypeCat.Fun X.obj Y.obj) X.obj Y.obj))
            _ _ _ (Hom.hom 1 : V (ofMulAction G (FintypeCat.of (G ⧸ N))) ⟶ V (ofMulAction G (FintypeCat.of (G ⧸ N)))) :
          (a : (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (ofMulAction G (FintypeCat.of (G ⧸ N))).V) →
            (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (ofMulAction G (FintypeCat.of (G ⧸ N))).V)
        x :
      (fun (X : ObjectProperty.FullSubcategory Finite) ↦ X.obj) (V (ofMulAction G (FintypeCat.of (G ⧸ N)))))

Tactic:
induction x using Quotient.inductionOn