intro a b c _ _ _ hab
case left
n : ℕ
round : ℕ → ℕ
npos : 0 < n
hfaithful₁ : faithful₁ n round
hcorrect₀ : correct₀ n round
hcorrect₁ : correct₁ n round
⊢ ∀ {a b c : ℕ}, trunc n a = a → trunc n b = b → trunc n c = c → a ≤ b → round (c - b) ≤ round (c - a)
case left
n : ℕ
round : ℕ → ℕ
npos : 0 < n
hfaithful₁ : faithful₁ n round
hcorrect₀ : correct₀ n round
hcorrect₁ : correct₁ n round
a b c : ℕ
a✝² : trunc n a = a
a✝¹ : trunc n b = b
a✝ : trunc n c = c
hab : a ≤ b
⊢ round (c - b) ≤ round (c - a)