rw [← condition_iff_weaker_le, ← condition_iff_weaker_ge]
d : ℕ
inst✝ : NeZero d
I : BasicInterval
hI : feasible d I
⊢ (∀ (a' b' : ℕ), mem_S_le d ↑a' ↑b' → mem a' b' I → a' * I.b₂ = b' * I.a₂) ∨
    ∀ (a' b' : ℕ), mem_S_ge d ↑a' ↑b' → mem a' b' I → a' * I.b₁ = b' * I.a₁
d : ℕ
inst✝ : NeZero d
I : BasicInterval
hI : feasible d I
⊢ (∀ (a b : ℕ), Nat.Coprime a b → mem_S_le d ↑a ↑b → mem a b I → a * I.b₂ = b * I.a₂) ∨
    ∀ (a b : ℕ), Nat.Coprime a b → mem_S_ge d ↑a ↑b → mem a b I → a * I.b₁ = b * I.a₁