{
  sorry
}
case inl
P : ℕ → Prop
n : ℕ
hind : ∀ (m : ℕ), m < n → 8 ≤ m → from_three_five m
h : 8 ≤ n
htri : n < 11
⊢ from_three_five n

case inr
P : ℕ → Prop
n : ℕ
hind : ∀ (m : ℕ), m < n → 8 ≤ m → from_three_five m
h : 8 ≤ n
htri : 11 ≤ n
⊢ from_three_five n
case inr
P : ℕ → Prop
n : ℕ
hind : ∀ (m : ℕ), m < n → 8 ≤ m → from_three_five m
h : 8 ≤ n
htri : 11 ≤ n
⊢ from_three_five n