clear a2_right
α : Type
L : Language α
n : ℕ
ih : ∀ s ∈ exp L n, s ∈ kleene_closure α L
s xs : Str α
a2_left : xs ∈ exp L n
a2_right : ∃ t ∈ L, xs ++ t = s
ys : Str α
a3 : ys ∈ L ∧ xs ++ ys = s
⊢ s ∈ kleene_closure α L
α : Type
L : Language α
n : ℕ
ih : ∀ s ∈ exp L n, s ∈ kleene_closure α L
s xs : Str α
a2_left : xs ∈ exp L n
ys : Str α
a3 : ys ∈ L ∧ xs ++ ys = s
⊢ s ∈ kleene_closure α L