intros a h₁
t : Th
Δ : Ctx
b : Lex (ℕ × ℕ)
⊢ ∀ (a : Lex (ℕ × ℕ)), a ≤ (0, 0) → lindenbaumSequence t Δ a ⊆ lindenbaumSequence t Δ (0, 0)
t : Th
Δ : Ctx
b a : Lex (ℕ × ℕ)
h₁ : a ≤ (0, 0)
⊢ lindenbaumSequence t Δ a ⊆ lindenbaumSequence t Δ (0, 0)