simp
α : Type u_1
β : Type u_2
G : group α
H : group β
hom : group_homomorphism G H
φ : α → β := group_homomorphism.fn G H
hphi : φ = group_homomorphism.fn G H
h : ∀ (x y : α), group_homomorphism.fn G H x = group_homomorphism.fn G H y → x = y
x : α
hker : φ x = has_one.one
hinj : has_one.one = φ x → has_one.one = x
hl : has_one.one = x
⊢ { mem := fun x s => Set.isMember x }.1 has_one.one (trivial_subgroup G)
α : Type u_1
β : Type u_2
G : group α
H : group β
hom : group_homomorphism G H
φ : α → β := group_homomorphism.fn G H
hphi : φ = group_homomorphism.fn G H
h : ∀ (x y : α), group_homomorphism.fn G H x = group_homomorphism.fn G H y → x = y
x : α
hker : φ x = has_one.one
hinj : has_one.one = φ x → has_one.one = x
hl : has_one.one = x
⊢ Set.isMember has_one.one