intros a h₁
t : Th
Δ : Ctx
b : Lex (ℕ × ℕ)
i j : ℕ
lem : lindenbaumSequence t Δ (i, j) ≤ lindenbaumSequence t Δ (i, j + 1)
⊢ ∀ (a : Lex (ℕ × ℕ)), a ≤ (i, j + 1) → lindenbaumSequence t Δ a ⊆ lindenbaumSequence t Δ (i, j + 1)
t : Th
Δ : Ctx
b : Lex (ℕ × ℕ)
i j : ℕ
lem : lindenbaumSequence t Δ (i, j) ≤ lindenbaumSequence t Δ (i, j + 1)
a : Lex (ℕ × ℕ)
h₁ : a ≤ (i, j + 1)
⊢ lindenbaumSequence t Δ a ⊆ lindenbaumSequence t Δ (i, j + 1)