have h₂ : a ≤ round (a - b) + b := by rwa [Nat.add_comm]
round : ℕ → ℕ
n a b : ℕ
npos : 0 < n
hfaithful₀ : faithful₀ n round
hfaithful₁ : faithful₁ n round
hfa : trunc n a = a
hba : 2 * b ≤ a
lt_round : a - b < round (a - b)
hba' : b ≤ a
h₁ : a ≤ b + round (a - b)
⊢ ulp n (a - b) - (a - b) % ulp n (a - b) ≤ b
round : ℕ → ℕ
n a b : ℕ
npos : 0 < n
hfaithful₀ : faithful₀ n round
hfaithful₁ : faithful₁ n round
hfa : trunc n a = a
hba : 2 * b ≤ a
lt_round : a - b < round (a - b)
hba' : b ≤ a
h₁ : a ≤ b + round (a - b)
h₂ : a ≤ round (a - b) + b
⊢ ulp n (a - b) - (a - b) % ulp n (a - b) ≤ b