exact b₁_lo_of_round_le_of_two_mul_le_of_ulp_le npos hfaithful₁
  hfa hfb round_lt.le two_mul_lt.le ulp_le
case inr.inr.inl.inr.inr.left.inr
round : ℕ → ℕ
n a b : ℕ
npos : 0 < n
hfaithful₀ : faithful₀ n round
hfaithful₁ : faithful₁ n round
hcorrect₀ : correct₀ n round
hfa : trunc n a = a
hfb : trunc n b = b
hba : b ≤ a
no_uflow : a - b ≥ 2 ^ n
bpos : b > 0
two_mul_lt : 2 * b < a
round_lt : round (a - b) < a - b
ulp_le : b ≥ ulp n (a - b)
⊢ trunc n (a - b - round (a - b)) = a - b - round (a - b)
no goals