simp
case inl
ι : Type u_1
α : Type u_2
inst✝¹ : CommGroup α
inst✝ : DecidableEq α
s✝ t : Finset α
a : α
s : Subgroup α
hst : ↑s ⊆ ↑∅.mulStab
⊢ image QuotientGroup.mk ∅.mulStab = (image QuotientGroup.mk ∅).mulStab
no goals