rcases hdvd3 with ⟨c, hc⟩
case inl
hwo : (∀ (a b c : ℕplus), (a ∣ b → b ∣ c → a ∣ c) ∧ (a ∣ b → b ∣ a → a = b)) ∧ ∀ (a b : ℕplus), a ∣ b ∨ b ∣ a
hdvd3 : ∃ c, 3 = 2 * c
⊢ False
case inl.intro
hwo : (∀ (a b c : ℕplus), (a ∣ b → b ∣ c → a ∣ c) ∧ (a ∣ b → b ∣ a → a = b)) ∧ ∀ (a b : ℕplus), a ∣ b ∨ b ∣ a
c : ℕplus
hc : 3 = 2 * c
⊢ False