Preparations for defining operations on Finset.

The operations here ignore multiplicities, and prepare for defining the corresponding operations on Finset.

finset insert

def Multiset.ndinsert {α : Type u_1} [DecidableEq α] (a : α) (s : Multiset α) : Multiset α

ndinsert a s is the lift of the list insert operation. This operation does not respect multiplicities, unlike cons, but it is suitable as an insert operation on Finset.

Equations

• Multiset.ndinsert a s = Quot.liftOn s (fun (l : List α) => ↑(List.insert a l)) ⋯

@[simp]

theorem Multiset.coe_ndinsert {α : Type u_1} [DecidableEq α] (a : α) (l : List α) : ndinsert a ↑l = ↑(insert a l)

@[simp]

theorem Multiset.ndinsert_zero {α : Type u_1} [DecidableEq α] (a : α) : ndinsert a 0 = {a}

@[simp]

theorem Multiset.ndinsert_of_mem {α : Type u_1} [DecidableEq α] {a : α} {s : Multiset α} : a ∈ s → ndinsert a s = s

@[simp]

theorem Multiset.ndinsert_of_notMem {α : Type u_1} [DecidableEq α] {a : α} {s : Multiset α} : a ∉ s → ndinsert a s = a ::ₘ s

@[deprecated Multiset.ndinsert_of_notMem (since := "2025-05-23")]

theorem Multiset.ndinsert_of_not_mem {α : Type u_1} [DecidableEq α] {a : α} {s : Multiset α} : a ∉ s → ndinsert a s = a ::ₘ s

Alias of Multiset.ndinsert_of_notMem.

@[simp]

theorem Multiset.mem_ndinsert {α : Type u_1} [DecidableEq α] {a b : α} {s : Multiset α} : a ∈ ndinsert b s ↔ a = b ∨ a ∈ s

@[simp]

theorem Multiset.le_ndinsert_self {α : Type u_1} [DecidableEq α] (a : α) (s : Multiset α) : s ≤ ndinsert a s

theorem Multiset.mem_ndinsert_self {α : Type u_1} [DecidableEq α] (a : α) (s : Multiset α) : a ∈ ndinsert a s

theorem Multiset.mem_ndinsert_of_mem {α : Type u_1} [DecidableEq α] {a b : α} {s : Multiset α} (h : a ∈ s) : a ∈ ndinsert b s

theorem Multiset.length_ndinsert_of_mem {α : Type u_1} [DecidableEq α] {a : α} {s : Multiset α} (h : a ∈ s) : (ndinsert a s).card = s.card

theorem Multiset.length_ndinsert_of_notMem {α : Type u_1} [DecidableEq α] {a : α} {s : Multiset α} (h : a ∉ s) : (ndinsert a s).card = s.card + 1

@[deprecated Multiset.length_ndinsert_of_notMem (since := "2025-05-23")]

theorem Multiset.length_ndinsert_of_not_mem {α : Type u_1} [DecidableEq α] {a : α} {s : Multiset α} (h : a ∉ s) : (ndinsert a s).card = s.card + 1

Alias of Multiset.length_ndinsert_of_notMem.

theorem Multiset.dedup_cons {α : Type u_1} [DecidableEq α] {a : α} {s : Multiset α} : (a ::ₘ s).dedup = ndinsert a s.dedup

theorem Multiset.Nodup.ndinsert {α : Type u_1} [DecidableEq α] {s : Multiset α} (a : α) : s.Nodup → (Multiset.ndinsert a s).Nodup

theorem Multiset.ndinsert_le {α : Type u_1} [DecidableEq α] {a : α} {s t : Multiset α} : ndinsert a s ≤ t ↔ s ≤ t ∧ a ∈ t

theorem Multiset.attach_ndinsert {α : Type u_1} [DecidableEq α] (a : α) (s : Multiset α) : (ndinsert a s).attach = ndinsert ⟨a, ⋯⟩ (map (fun (p : { x : α // x ∈ s }) => ⟨↑p, ⋯⟩) s.attach)

@[simp]

theorem Multiset.disjoint_ndinsert_left {α : Type u_1} [DecidableEq α] {a : α} {s t : Multiset α} : Disjoint (ndinsert a s) t ↔ a ∉ t ∧ Disjoint s t

@[simp]

theorem Multiset.disjoint_ndinsert_right {α : Type u_1} [DecidableEq α] {a : α} {s t : Multiset α} : Disjoint s (ndinsert a t) ↔ a ∉ s ∧ Disjoint s t

finset union

def Multiset.ndunion {α : Type u_1} [DecidableEq α] (s t : Multiset α) : Multiset α

ndunion s t is the lift of the list union operation. This operation does not respect multiplicities, unlike s ∪ t, but it is suitable as a union operation on Finset. (s ∪ t would also work as a union operation on finset, but this is more efficient.)

Equations

• s.ndunion t = Quotient.liftOn₂ s t (fun (l₁ l₂ : List α) => ↑(l₁.union l₂)) ⋯

@[simp]

theorem Multiset.coe_ndunion {α : Type u_1} [DecidableEq α] (l₁ l₂ : List α) : (↑l₁).ndunion ↑l₂ = ↑(l₁ ∪ l₂)

theorem Multiset.zero_ndunion {α : Type u_1} [DecidableEq α] (s : Multiset α) : ndunion 0 s = s

@[simp]

theorem Multiset.cons_ndunion {α : Type u_1} [DecidableEq α] (s t : Multiset α) (a : α) : (a ::ₘ s).ndunion t = ndinsert a (s.ndunion t)

@[simp]

theorem Multiset.mem_ndunion {α : Type u_1} [DecidableEq α] {s t : Multiset α} {a : α} : a ∈ s.ndunion t ↔ a ∈ s ∨ a ∈ t

theorem Multiset.le_ndunion_right {α : Type u_1} [DecidableEq α] (s t : Multiset α) : t ≤ s.ndunion t

theorem Multiset.subset_ndunion_right {α : Type u_1} [DecidableEq α] (s t : Multiset α) : t ⊆ s.ndunion t

theorem Multiset.ndunion_le_add {α : Type u_1} [DecidableEq α] (s t : Multiset α) : s.ndunion t ≤ s + t

theorem Multiset.ndunion_le {α : Type u_1} [DecidableEq α] {s t u : Multiset α} : s.ndunion t ≤ u ↔ s ⊆ u ∧ t ≤ u

theorem Multiset.subset_ndunion_left {α : Type u_1} [DecidableEq α] (s t : Multiset α) : s ⊆ s.ndunion t

theorem Multiset.le_ndunion_left {α : Type u_1} [DecidableEq α] {s : Multiset α} (t : Multiset α) (d : s.Nodup) : s ≤ s.ndunion t

theorem Multiset.ndunion_le_union {α : Type u_1} [DecidableEq α] (s t : Multiset α) : s.ndunion t ≤ s ∪ t

theorem Multiset.Nodup.ndunion {α : Type u_1} [DecidableEq α] (s : Multiset α) {t : Multiset α} : t.Nodup → (s.ndunion t).Nodup

@[simp]

theorem Multiset.ndunion_eq_union {α : Type u_1} [DecidableEq α] {s t : Multiset α} (d : s.Nodup) : s.ndunion t = s ∪ t

theorem Multiset.dedup_add {α : Type u_1} [DecidableEq α] (s t : Multiset α) : (s + t).dedup = s.ndunion t.dedup

theorem Multiset.Disjoint.ndunion_eq {α : Type u_1} [DecidableEq α] {s t : Multiset α} (h : Disjoint s t) : s.ndunion t = s.dedup + t

theorem Multiset.Subset.ndunion_eq_right {α : Type u_1} [DecidableEq α] {s t : Multiset α} (h : s ⊆ t) : s.ndunion t = t

finset inter

def Multiset.ndinter {α : Type u_1} [DecidableEq α] (s t : Multiset α) : Multiset α

ndinter s t is the lift of the list ∩ operation. This operation does not respect multiplicities, unlike s ∩ t, but it is suitable as an intersection operation on Finset. (s ∩ t would also work as an intersection operation on finset, but this is more efficient.)

Equations

• s.ndinter t = Multiset.filter (fun (x : α) => x ∈ t) s

@[simp]

theorem Multiset.coe_ndinter {α : Type u_1} [DecidableEq α] (l₁ l₂ : List α) : (↑l₁).ndinter ↑l₂ = ↑(l₁ ∩ l₂)

@[simp]

theorem Multiset.zero_ndinter {α : Type u_1} [DecidableEq α] (s : Multiset α) : ndinter 0 s = 0

@[simp]

theorem Multiset.cons_ndinter_of_mem {α : Type u_1} [DecidableEq α] {a : α} (s : Multiset α) {t : Multiset α} (h : a ∈ t) : (a ::ₘ s).ndinter t = a ::ₘ s.ndinter t

@[simp]

theorem Multiset.ndinter_cons_of_notMem {α : Type u_1} [DecidableEq α] {a : α} (s : Multiset α) {t : Multiset α} (h : a ∉ t) : (a ::ₘ s).ndinter t = s.ndinter t

@[deprecated Multiset.ndinter_cons_of_notMem (since := "2025-05-23")]

theorem Multiset.ndinter_cons_of_not_mem {α : Type u_1} [DecidableEq α] {a : α} (s : Multiset α) {t : Multiset α} (h : a ∉ t) : (a ::ₘ s).ndinter t = s.ndinter t

Alias of Multiset.ndinter_cons_of_notMem.

@[simp]

theorem Multiset.mem_ndinter {α : Type u_1} [DecidableEq α] {s t : Multiset α} {a : α} : a ∈ s.ndinter t ↔ a ∈ s ∧ a ∈ t

theorem Multiset.Nodup.ndinter {α : Type u_1} [DecidableEq α] {s : Multiset α} (t : Multiset α) : s.Nodup → (s.ndinter t).Nodup

theorem Multiset.le_ndinter {α : Type u_1} [DecidableEq α] {s t u : Multiset α} : s ≤ t.ndinter u ↔ s ≤ t ∧ s ⊆ u

theorem Multiset.ndinter_le_left {α : Type u_1} [DecidableEq α] (s t : Multiset α) : s.ndinter t ≤ s

theorem Multiset.ndinter_subset_left {α : Type u_1} [DecidableEq α] (s t : Multiset α) : s.ndinter t ⊆ s

theorem Multiset.ndinter_subset_right {α : Type u_1} [DecidableEq α] (s t : Multiset α) : s.ndinter t ⊆ t

theorem Multiset.ndinter_le_right {α : Type u_1} [DecidableEq α] {s : Multiset α} (t : Multiset α) (d : s.Nodup) : s.ndinter t ≤ t

theorem Multiset.inter_le_ndinter {α : Type u_1} [DecidableEq α] (s t : Multiset α) : s ∩ t ≤ s.ndinter t

@[simp]

theorem Multiset.ndinter_eq_inter {α : Type u_1} [DecidableEq α] {s t : Multiset α} (d : s.Nodup) : s.ndinter t = s ∩ t

@[simp]

theorem Multiset.Nodup.inter {α : Type u_1} [DecidableEq α] {s : Multiset α} (t : Multiset α) (d : s.Nodup) : (s ∩ t).Nodup

theorem Multiset.ndinter_eq_zero_iff_disjoint {α : Type u_1} [DecidableEq α] {s t : Multiset α} : s.ndinter t = 0 ↔ Disjoint s t

theorem Multiset.Disjoint.ndinter_eq_zero {α : Type u_1} [DecidableEq α] {s t : Multiset α} : Disjoint s t → s.ndinter t = 0

Alias of the reverse direction of Multiset.ndinter_eq_zero_iff_disjoint.

theorem Multiset.Subset.ndinter_eq_left {α : Type u_1} [DecidableEq α] {s t : Multiset α} (h : s ⊆ t) : s.ndinter t = s