simp only [zero_mul]
case inl.intro
d : ℕ
inst✝ : NeZero d
I : BasicInterval
H : ∀ (a b : ℕ), Nat.Coprime a b → mem_S_le d ↑a ↑b → mem a b I → a * I.b₂ = b * I.a₂
h₁ : mem_S_le d ↑0 ↑0
h₂ : mem 0 0 I
h₀ : Nat.gcd 0 0 = 0
⊢ 0 * I.b₂ = 0 * I.a₂
no goals