a : ℕ
m : Multiset ℕ
x : ℕ
hxa : x ∈ range a
hxb : x ∈ map (fun x => a + x) m
⊢ False
a : ℕ
m : Multiset ℕ
⊢ Disjoint (range a) (map (fun x => a + x) m)
intro x hxa hxb
a : ℕ
m : Multiset ℕ
x : ℕ
hxa : x < a
hxb : x ∈ map (fun x => a + x) m
⊢ False
a : ℕ
m : Multiset ℕ
x : ℕ
hxa : x ∈ range a
hxb : x ∈ map (fun x => a + x) m
⊢ False
rw [range, mem_coe, List.mem_range] at hxa
case intro.intro
a : ℕ
m : Multiset ℕ
c : ℕ
left✝ : c ∈ m
hxa : a + c < a
hxb : a + c ∈ map (fun x => a + x) m
⊢ False
a : ℕ
m : Multiset ℕ
x : ℕ
hxa : x < a
hxb : x ∈ map (fun x => a + x) m
⊢ False
obtain ⟨c, _, rfl⟩ := mem_map.1 hxb
no goals
case intro.intro
a : ℕ
m : Multiset ℕ
c : ℕ
left✝ : c ∈ m
hxa : a + c < a
hxb : a + c ∈ map (fun x => a + x) m
⊢ False
exact (self_le_add_right _ _).not_lt hxa