exact sterbenz hfc hfa hac hca
round : ℕ → ℕ
n a b : ℕ
npos : 0 < n
hfaithful₀ : faithful₀ n round
hfaithful₁ : faithful₁ n round
hcorrect₁ : correct₁ n round
hfa : trunc n a = a
hfb : trunc n b = b
hba : b ≤ a
hi : a + b ≤ round (a + b)
hac : a ≤ round (a + b)
hca : round (a + b) ≤ 2 * a
hfc : trunc n (round (a + b)) = round (a + b)
⊢ trunc n (round (a + b) - a) = round (a + b) - a
no goals