intro n hn
case cons.nil
b a x : ℕ
hl_mono : List.Chain (fun u v => u < v) a [x]
hl_slow : List.Chain (fun u v => v ≤ 2 * u) a [x]
hl_cons : [x] ≠ []
hb : b < List.getLast [x] hl_cons
⊢ ∀ (n : ℕ), n ∈ Set.Icc a b → ∃ lᵢ, lᵢ ∈ [x] ∧ lᵢ ∈ Set.Ioc n (2 * n)
case cons.nil
b a x : ℕ
hl_mono : List.Chain (fun u v => u < v) a [x]
hl_slow : List.Chain (fun u v => v ≤ 2 * u) a [x]
hl_cons : [x] ≠ []
hb : b < List.getLast [x] hl_cons
n : ℕ
hn : n ∈ Set.Icc a b
⊢ ∃ lᵢ, lᵢ ∈ [x] ∧ lᵢ ∈ Set.Ioc n (2 * n)