apply ulp_dvd_ulp
round : ℕ → ℕ
n a b : ℕ
npos : 0 < n
hfaithful₀ : faithful₀ n round
hfaithful₁ : faithful₁ n round
hfa : trunc n a = a
hfb : trunc n b = b
hba : 2 * b ≤ a
lt_round : a - b < round (a - b)
⊢ ulp n b ∣ ulp n (a - b)
case h
round : ℕ → ℕ
n a b : ℕ
npos : 0 < n
hfaithful₀ : faithful₀ n round
hfaithful₁ : faithful₁ n round
hfa : trunc n a = a
hfb : trunc n b = b
hba : 2 * b ≤ a
lt_round : a - b < round (a - b)
⊢ b ≤ a - b