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Mathlib.Algebra.BigOperators.Multiset.Basic

Sums and products over multisets #

In this file we define products and sums indexed by multisets. This is later used to define products and sums indexed by finite sets.

Main declarations #

Implementation notes #

Nov 2022: To speed the Lean 4 port, lemmas requiring extra algebra imports (data.list.big_operators.lemmas rather than .basic) have been moved to a separate file, algebra.big_operators.multiset.lemmas. This split does not need to be permanent.

theorem Multiset.sum.proof_1 {α : Type u_1} [AddCommMonoid α] (x : α) (y : α) (z : α) :
x + (y + z) = y + (x + z)
def Multiset.sum {α : Type u_2} [AddCommMonoid α] :
Multiset αα

Sum of a multiset given a commutative additive monoid structure on α. sum {a, b, c} = a + b + c

Equations
Instances For
    def Multiset.prod {α : Type u_2} [CommMonoid α] :
    Multiset αα

    Product of a multiset given a commutative monoid structure on α. prod {a, b, c} = a * b * c

    Equations
    • Multiset.prod = Multiset.foldr (fun x x_1 => x * x_1) (_ : ∀ (x y z : α), x * (y * z) = y * (x * z)) 1
    Instances For
      theorem Multiset.sum_eq_foldr {α : Type u_2} [AddCommMonoid α] (s : Multiset α) :
      Multiset.sum s = Multiset.foldr (fun x x_1 => x + x_1) (_ : ∀ (x y z : α), x + (y + z) = y + (x + z)) 0 s
      theorem Multiset.prod_eq_foldr {α : Type u_2} [CommMonoid α] (s : Multiset α) :
      Multiset.prod s = Multiset.foldr (fun x x_1 => x * x_1) (_ : ∀ (x y z : α), x * (y * z) = y * (x * z)) 1 s
      theorem Multiset.sum_eq_foldl {α : Type u_2} [AddCommMonoid α] (s : Multiset α) :
      Multiset.sum s = Multiset.foldl (fun x x_1 => x + x_1) (_ : ∀ (x y z : α), x + y + z = x + z + y) 0 s
      theorem Multiset.prod_eq_foldl {α : Type u_2} [CommMonoid α] (s : Multiset α) :
      Multiset.prod s = Multiset.foldl (fun x x_1 => x * x_1) (_ : ∀ (x y z : α), x * y * z = x * z * y) 1 s
      @[simp]
      theorem Multiset.coe_sum {α : Type u_2} [AddCommMonoid α] (l : List α) :
      @[simp]
      theorem Multiset.coe_prod {α : Type u_2} [CommMonoid α] (l : List α) :
      @[simp]
      theorem Multiset.sum_zero {α : Type u_2} [AddCommMonoid α] :
      @[simp]
      theorem Multiset.prod_zero {α : Type u_2} [CommMonoid α] :
      @[simp]
      theorem Multiset.sum_cons {α : Type u_2} [AddCommMonoid α] (a : α) (s : Multiset α) :
      @[simp]
      theorem Multiset.prod_cons {α : Type u_2} [CommMonoid α] (a : α) (s : Multiset α) :
      @[simp]
      theorem Multiset.sum_erase {α : Type u_2} [AddCommMonoid α] {s : Multiset α} {a : α} [DecidableEq α] (h : a s) :
      @[simp]
      theorem Multiset.prod_erase {α : Type u_2} [CommMonoid α] {s : Multiset α} {a : α} [DecidableEq α] (h : a s) :
      @[simp]
      theorem Multiset.sum_map_erase {ι : Type u_1} {α : Type u_2} [AddCommMonoid α] {m : Multiset ι} {f : ια} [DecidableEq ι] {a : ι} (h : a m) :
      @[simp]
      theorem Multiset.prod_map_erase {ι : Type u_1} {α : Type u_2} [CommMonoid α] {m : Multiset ι} {f : ια} [DecidableEq ι] {a : ι} (h : a m) :
      @[simp]
      theorem Multiset.sum_singleton {α : Type u_2} [AddCommMonoid α] (a : α) :
      @[simp]
      theorem Multiset.prod_singleton {α : Type u_2} [CommMonoid α] (a : α) :
      theorem Multiset.sum_pair {α : Type u_2} [AddCommMonoid α] (a : α) (b : α) :
      Multiset.sum {a, b} = a + b
      theorem Multiset.prod_pair {α : Type u_2} [CommMonoid α] (a : α) (b : α) :
      Multiset.prod {a, b} = a * b
      @[simp]
      theorem Multiset.sum_add {α : Type u_2} [AddCommMonoid α] (s : Multiset α) (t : Multiset α) :
      @[simp]
      theorem Multiset.prod_add {α : Type u_2} [CommMonoid α] (s : Multiset α) (t : Multiset α) :
      theorem Multiset.prod_nsmul {α : Type u_2} [CommMonoid α] (m : Multiset α) (n : ) :
      @[simp]
      theorem Multiset.sum_replicate {α : Type u_2} [AddCommMonoid α] (n : ) (a : α) :
      @[simp]
      theorem Multiset.prod_replicate {α : Type u_2} [CommMonoid α] (n : ) (a : α) :
      theorem Multiset.sum_map_eq_nsmul_single {ι : Type u_1} {α : Type u_2} [AddCommMonoid α] {m : Multiset ι} {f : ια} [DecidableEq ι] (i : ι) (hf : ∀ (i' : ι), i' ii' mf i' = 0) :
      theorem Multiset.prod_map_eq_pow_single {ι : Type u_1} {α : Type u_2} [CommMonoid α] {m : Multiset ι} {f : ια} [DecidableEq ι] (i : ι) (hf : ∀ (i' : ι), i' ii' mf i' = 1) :
      theorem Multiset.sum_eq_nsmul_single {α : Type u_2} [AddCommMonoid α] {s : Multiset α} [DecidableEq α] (a : α) (h : ∀ (a' : α), a' aa' sa' = 0) :
      theorem Multiset.prod_eq_pow_single {α : Type u_2} [CommMonoid α] {s : Multiset α} [DecidableEq α] (a : α) (h : ∀ (a' : α), a' aa' sa' = 1) :
      theorem Multiset.pow_count {α : Type u_2} [CommMonoid α] {s : Multiset α} [DecidableEq α] (a : α) :
      theorem Multiset.sum_hom {α : Type u_2} {β : Type u_3} [AddCommMonoid α] [AddCommMonoid β] (s : Multiset α) {F : Type u_5} [AddMonoidHomClass F α β] (f : F) :
      theorem Multiset.prod_hom {α : Type u_2} {β : Type u_3} [CommMonoid α] [CommMonoid β] (s : Multiset α) {F : Type u_5} [MonoidHomClass F α β] (f : F) :
      theorem Multiset.sum_hom' {ι : Type u_1} {α : Type u_2} {β : Type u_3} [AddCommMonoid α] [AddCommMonoid β] (s : Multiset ι) {F : Type u_5} [AddMonoidHomClass F α β] (f : F) (g : ια) :
      Multiset.sum (Multiset.map (fun i => f (g i)) s) = f (Multiset.sum (Multiset.map g s))
      theorem Multiset.prod_hom' {ι : Type u_1} {α : Type u_2} {β : Type u_3} [CommMonoid α] [CommMonoid β] (s : Multiset ι) {F : Type u_5} [MonoidHomClass F α β] (f : F) (g : ια) :
      Multiset.prod (Multiset.map (fun i => f (g i)) s) = f (Multiset.prod (Multiset.map g s))
      theorem Multiset.sum_hom₂ {ι : Type u_1} {α : Type u_2} {β : Type u_3} {γ : Type u_4} [AddCommMonoid α] [AddCommMonoid β] [AddCommMonoid γ] (s : Multiset ι) (f : αβγ) (hf : ∀ (a b : α) (c d : β), f (a + b) (c + d) = f a c + f b d) (hf' : f 0 0 = 0) (f₁ : ια) (f₂ : ιβ) :
      Multiset.sum (Multiset.map (fun i => f (f₁ i) (f₂ i)) s) = f (Multiset.sum (Multiset.map f₁ s)) (Multiset.sum (Multiset.map f₂ s))
      theorem Multiset.prod_hom₂ {ι : Type u_1} {α : Type u_2} {β : Type u_3} {γ : Type u_4} [CommMonoid α] [CommMonoid β] [CommMonoid γ] (s : Multiset ι) (f : αβγ) (hf : ∀ (a b : α) (c d : β), f (a * b) (c * d) = f a c * f b d) (hf' : f 1 1 = 1) (f₁ : ια) (f₂ : ιβ) :
      Multiset.prod (Multiset.map (fun i => f (f₁ i) (f₂ i)) s) = f (Multiset.prod (Multiset.map f₁ s)) (Multiset.prod (Multiset.map f₂ s))
      theorem Multiset.sum_hom_rel {ι : Type u_1} {α : Type u_2} {β : Type u_3} [AddCommMonoid α] [AddCommMonoid β] (s : Multiset ι) {r : αβProp} {f : ια} {g : ιβ} (h₁ : r 0 0) (h₂ : a : ι⦄ → b : α⦄ → c : β⦄ → r b cr (f a + b) (g a + c)) :
      theorem Multiset.prod_hom_rel {ι : Type u_1} {α : Type u_2} {β : Type u_3} [CommMonoid α] [CommMonoid β] (s : Multiset ι) {r : αβProp} {f : ια} {g : ιβ} (h₁ : r 1 1) (h₂ : a : ι⦄ → b : α⦄ → c : β⦄ → r b cr (f a * b) (g a * c)) :
      theorem Multiset.sum_map_zero {ι : Type u_1} {α : Type u_2} [AddCommMonoid α] {m : Multiset ι} :
      Multiset.sum (Multiset.map (fun x => 0) m) = 0
      theorem Multiset.prod_map_one {ι : Type u_1} {α : Type u_2} [CommMonoid α] {m : Multiset ι} :
      Multiset.prod (Multiset.map (fun x => 1) m) = 1
      @[simp]
      theorem Multiset.sum_map_add {ι : Type u_1} {α : Type u_2} [AddCommMonoid α] {m : Multiset ι} {f : ια} {g : ια} :
      @[simp]
      theorem Multiset.prod_map_mul {ι : Type u_1} {α : Type u_2} [CommMonoid α] {m : Multiset ι} {f : ια} {g : ια} :
      @[simp]
      theorem Multiset.prod_map_neg {α : Type u_2} [CommMonoid α] [HasDistribNeg α] (s : Multiset α) :
      Multiset.prod (Multiset.map Neg.neg s) = (-1) ^ Multiset.card s * Multiset.prod s
      theorem Multiset.sum_map_nsmul {ι : Type u_1} {α : Type u_2} [AddCommMonoid α] {m : Multiset ι} {f : ια} {n : } :
      theorem Multiset.prod_map_pow {ι : Type u_1} {α : Type u_2} [CommMonoid α] {m : Multiset ι} {f : ια} {n : } :
      theorem Multiset.sum_map_sum_map {α : Type u_2} {β : Type u_3} {γ : Type u_4} [AddCommMonoid α] (m : Multiset β) (n : Multiset γ) {f : βγα} :
      Multiset.sum (Multiset.map (fun a => Multiset.sum (Multiset.map (fun b => f a b) n)) m) = Multiset.sum (Multiset.map (fun b => Multiset.sum (Multiset.map (fun a => f a b) m)) n)
      theorem Multiset.prod_map_prod_map {α : Type u_2} {β : Type u_3} {γ : Type u_4} [CommMonoid α] (m : Multiset β) (n : Multiset γ) {f : βγα} :
      Multiset.prod (Multiset.map (fun a => Multiset.prod (Multiset.map (fun b => f a b) n)) m) = Multiset.prod (Multiset.map (fun b => Multiset.prod (Multiset.map (fun a => f a b) m)) n)
      theorem Multiset.sum_induction {α : Type u_2} [AddCommMonoid α] (p : αProp) (s : Multiset α) (p_mul : (a b : α) → p ap bp (a + b)) (p_one : p 0) (p_s : (a : α) → a sp a) :
      theorem Multiset.prod_induction {α : Type u_2} [CommMonoid α] (p : αProp) (s : Multiset α) (p_mul : (a b : α) → p ap bp (a * b)) (p_one : p 1) (p_s : (a : α) → a sp a) :
      theorem Multiset.sum_induction_nonempty {α : Type u_2} [AddCommMonoid α] {s : Multiset α} (p : αProp) (p_mul : (a b : α) → p ap bp (a + b)) (hs : s ) (p_s : (a : α) → a sp a) :
      theorem Multiset.prod_induction_nonempty {α : Type u_2} [CommMonoid α] {s : Multiset α} (p : αProp) (p_mul : (a b : α) → p ap bp (a * b)) (hs : s ) (p_s : (a : α) → a sp a) :
      theorem Multiset.prod_dvd_prod_of_le {α : Type u_2} [CommMonoid α] {s : Multiset α} {t : Multiset α} (h : s t) :
      theorem Multiset.prod_dvd_prod_of_dvd {α : Type u_2} {β : Type u_3} [CommMonoid β] {S : Multiset α} (g1 : αβ) (g2 : αβ) (h : ∀ (a : α), a Sg1 a g2 a) :

      Multiset.sum, the sum of the elements of a multiset, promoted to a morphism of AddCommMonoids.

      Equations
      • One or more equations did not get rendered due to their size.
      Instances For
        @[simp]
        theorem Multiset.coe_sumAddMonoidHom {α : Type u_2} [AddCommMonoid α] :
        Multiset.sumAddMonoidHom = Multiset.sum
        theorem Multiset.prod_eq_zero {α : Type u_2} [CommMonoidWithZero α] {s : Multiset α} (h : 0 s) :
        @[simp]
        theorem Multiset.sum_map_neg {ι : Type u_1} {α : Type u_2} [SubtractionCommMonoid α] {m : Multiset ι} {f : ια} :
        @[simp]
        theorem Multiset.prod_map_inv {ι : Type u_1} {α : Type u_2} [DivisionCommMonoid α] {m : Multiset ι} {f : ια} :
        @[simp]
        theorem Multiset.sum_map_sub {ι : Type u_1} {α : Type u_2} [SubtractionCommMonoid α] {m : Multiset ι} {f : ια} {g : ια} :
        @[simp]
        theorem Multiset.prod_map_div {ι : Type u_1} {α : Type u_2} [DivisionCommMonoid α] {m : Multiset ι} {f : ια} {g : ια} :
        theorem Multiset.sum_map_zsmul {ι : Type u_1} {α : Type u_2} [SubtractionCommMonoid α] {m : Multiset ι} {f : ια} {n : } :
        theorem Multiset.prod_map_zpow {ι : Type u_1} {α : Type u_2} [DivisionCommMonoid α] {m : Multiset ι} {f : ια} {n : } :
        theorem Multiset.sum_map_mul_left {ι : Type u_1} {α : Type u_2} [NonUnitalNonAssocSemiring α] {a : α} {s : Multiset ι} {f : ια} :
        Multiset.sum (Multiset.map (fun i => a * f i) s) = a * Multiset.sum (Multiset.map f s)
        theorem Multiset.sum_map_mul_right {ι : Type u_1} {α : Type u_2} [NonUnitalNonAssocSemiring α] {a : α} {s : Multiset ι} {f : ια} :
        Multiset.sum (Multiset.map (fun i => f i * a) s) = Multiset.sum (Multiset.map f s) * a
        theorem Multiset.dvd_sum {α : Type u_2} [NonUnitalSemiring α] {a : α} {s : Multiset α} :
        (∀ (x : α), x sa x) → a Multiset.sum s

        Order #

        theorem Multiset.sum_nonneg {α : Type u_2} [OrderedAddCommMonoid α] {s : Multiset α} :
        (∀ (x : α), x s0 x) → 0 Multiset.sum s
        theorem Multiset.one_le_prod_of_one_le {α : Type u_2} [OrderedCommMonoid α] {s : Multiset α} :
        (∀ (x : α), x s1 x) → 1 Multiset.prod s
        theorem Multiset.single_le_sum {α : Type u_2} [OrderedAddCommMonoid α] {s : Multiset α} :
        (∀ (x : α), x s0 x) → ∀ (x : α), x sx Multiset.sum s
        theorem Multiset.single_le_prod {α : Type u_2} [OrderedCommMonoid α] {s : Multiset α} :
        (∀ (x : α), x s1 x) → ∀ (x : α), x sx Multiset.prod s
        theorem Multiset.sum_le_card_nsmul {α : Type u_2} [OrderedAddCommMonoid α] (s : Multiset α) (n : α) (h : ∀ (x : α), x sx n) :
        Multiset.sum s Multiset.card s n
        theorem Multiset.prod_le_pow_card {α : Type u_2} [OrderedCommMonoid α] (s : Multiset α) (n : α) (h : ∀ (x : α), x sx n) :
        Multiset.prod s n ^ Multiset.card s
        theorem Multiset.all_zero_of_le_zero_le_of_sum_eq_zero {α : Type u_2} [OrderedAddCommMonoid α] {s : Multiset α} :
        (∀ (x : α), x s0 x) → Multiset.sum s = 0∀ (x : α), x sx = 0
        theorem Multiset.all_one_of_le_one_le_of_prod_eq_one {α : Type u_2} [OrderedCommMonoid α] {s : Multiset α} :
        (∀ (x : α), x s1 x) → Multiset.prod s = 1∀ (x : α), x sx = 1
        theorem Multiset.sum_le_sum_of_rel_le {α : Type u_2} [OrderedAddCommMonoid α] {s : Multiset α} {t : Multiset α} (h : Multiset.Rel (fun x x_1 => x x_1) s t) :
        theorem Multiset.prod_le_prod_of_rel_le {α : Type u_2} [OrderedCommMonoid α] {s : Multiset α} {t : Multiset α} (h : Multiset.Rel (fun x x_1 => x x_1) s t) :
        theorem Multiset.sum_map_le_sum_map {ι : Type u_1} {α : Type u_2} [OrderedAddCommMonoid α] {s : Multiset ι} (f : ια) (g : ια) (h : ∀ (i : ι), i sf i g i) :
        theorem Multiset.prod_map_le_prod_map {ι : Type u_1} {α : Type u_2} [OrderedCommMonoid α] {s : Multiset ι} (f : ια) (g : ια) (h : ∀ (i : ι), i sf i g i) :
        theorem Multiset.sum_map_le_sum {α : Type u_2} [OrderedAddCommMonoid α] {s : Multiset α} (f : αα) (h : ∀ (x : α), x sf x x) :
        theorem Multiset.prod_map_le_prod {α : Type u_2} [OrderedCommMonoid α] {s : Multiset α} (f : αα) (h : ∀ (x : α), x sf x x) :
        theorem Multiset.sum_le_sum_map {α : Type u_2} [OrderedAddCommMonoid α] {s : Multiset α} (f : αα) (h : ∀ (x : α), x sx f x) :
        theorem Multiset.prod_le_prod_map {α : Type u_2} [OrderedCommMonoid α] {s : Multiset α} (f : αα) (h : ∀ (x : α), x sx f x) :
        theorem Multiset.card_nsmul_le_sum {α : Type u_2} [OrderedAddCommMonoid α] {s : Multiset α} {a : α} (h : ∀ (x : α), x sa x) :
        Multiset.card s a Multiset.sum s
        theorem Multiset.pow_card_le_prod {α : Type u_2} [OrderedCommMonoid α] {s : Multiset α} {a : α} (h : ∀ (x : α), x sa x) :
        a ^ Multiset.card s Multiset.prod s
        theorem Multiset.prod_nonneg {α : Type u_2} [OrderedCommSemiring α] {m : Multiset α} (h : ∀ (a : α), a m0 a) :
        theorem Multiset.sum_eq_zero {α : Type u_2} [AddCommMonoid α] {m : Multiset α} (h : ∀ (x : α), x mx = 0) :

        Slightly more general version of Multiset.sum_eq_zero_iff for a non-ordered AddMonoid

        theorem Multiset.prod_eq_one {α : Type u_2} [CommMonoid α] {m : Multiset α} (h : ∀ (x : α), x mx = 1) :

        Slightly more general version of Multiset.prod_eq_one_iff for a non-ordered Monoid

        theorem Multiset.le_sum_of_mem {α : Type u_2} [CanonicallyOrderedAddMonoid α] {m : Multiset α} {a : α} (h : a m) :
        theorem Multiset.le_prod_of_mem {α : Type u_2} [CanonicallyOrderedMonoid α] {m : Multiset α} {a : α} (h : a m) :
        theorem Multiset.le_sum_of_subadditive_on_pred {α : Type u_2} {β : Type u_3} [AddCommMonoid α] [OrderedAddCommMonoid β] (f : αβ) (p : αProp) (h_one : f 0 = 0) (hp_one : p 0) (h_mul : ∀ (a b : α), p ap bf (a + b) f a + f b) (hp_mul : (a b : α) → p ap bp (a + b)) (s : Multiset α) (hps : (a : α) → a sp a) :
        theorem Multiset.le_prod_of_submultiplicative_on_pred {α : Type u_2} {β : Type u_3} [CommMonoid α] [OrderedCommMonoid β] (f : αβ) (p : αProp) (h_one : f 1 = 1) (hp_one : p 1) (h_mul : ∀ (a b : α), p ap bf (a * b) f a * f b) (hp_mul : (a b : α) → p ap bp (a * b)) (s : Multiset α) (hps : (a : α) → a sp a) :
        theorem Multiset.le_sum_of_subadditive {α : Type u_2} {β : Type u_3} [AddCommMonoid α] [OrderedAddCommMonoid β] (f : αβ) (h_one : f 0 = 0) (h_mul : ∀ (a b : α), f (a + b) f a + f b) (s : Multiset α) :
        theorem Multiset.le_prod_of_submultiplicative {α : Type u_2} {β : Type u_3} [CommMonoid α] [OrderedCommMonoid β] (f : αβ) (h_one : f 1 = 1) (h_mul : ∀ (a b : α), f (a * b) f a * f b) (s : Multiset α) :
        theorem Multiset.le_sum_nonempty_of_subadditive_on_pred {α : Type u_2} {β : Type u_3} [AddCommMonoid α] [OrderedAddCommMonoid β] (f : αβ) (p : αProp) (h_mul : ∀ (a b : α), p ap bf (a + b) f a + f b) (hp_mul : (a b : α) → p ap bp (a + b)) (s : Multiset α) (hs_nonempty : s ) (hs : (a : α) → a sp a) :
        theorem Multiset.le_prod_nonempty_of_submultiplicative_on_pred {α : Type u_2} {β : Type u_3} [CommMonoid α] [OrderedCommMonoid β] (f : αβ) (p : αProp) (h_mul : ∀ (a b : α), p ap bf (a * b) f a * f b) (hp_mul : (a b : α) → p ap bp (a * b)) (s : Multiset α) (hs_nonempty : s ) (hs : (a : α) → a sp a) :
        theorem Multiset.le_sum_nonempty_of_subadditive {α : Type u_2} {β : Type u_3} [AddCommMonoid α] [OrderedAddCommMonoid β] (f : αβ) (h_mul : ∀ (a b : α), f (a + b) f a + f b) (s : Multiset α) (hs_nonempty : s ) :
        theorem Multiset.le_prod_nonempty_of_submultiplicative {α : Type u_2} {β : Type u_3} [CommMonoid α] [OrderedCommMonoid β] (f : αβ) (h_mul : ∀ (a b : α), f (a * b) f a * f b) (s : Multiset α) (hs_nonempty : s ) :
        @[simp]
        theorem Multiset.sum_map_singleton {α : Type u_2} (s : Multiset α) :
        Multiset.sum (Multiset.map (fun a => {a}) s) = s
        theorem Multiset.sum_nat_mod (s : Multiset ) (n : ) :
        Multiset.sum s % n = Multiset.sum (Multiset.map (fun x => x % n) s) % n
        theorem Multiset.prod_nat_mod (s : Multiset ) (n : ) :
        Multiset.prod s % n = Multiset.prod (Multiset.map (fun x => x % n) s) % n
        theorem Multiset.sum_int_mod (s : Multiset ) (n : ) :
        Multiset.sum s % n = Multiset.sum (Multiset.map (fun x => x % n) s) % n
        theorem Multiset.prod_int_mod (s : Multiset ) (n : ) :
        Multiset.prod s % n = Multiset.prod (Multiset.map (fun x => x % n) s) % n
        theorem map_multiset_sum {α : Type u_2} {β : Type u_3} [AddCommMonoid α] [AddCommMonoid β] {F : Type u_5} [AddMonoidHomClass F α β] (f : F) (s : Multiset α) :
        theorem map_multiset_prod {α : Type u_2} {β : Type u_3} [CommMonoid α] [CommMonoid β] {F : Type u_5} [MonoidHomClass F α β] (f : F) (s : Multiset α) :
        theorem AddMonoidHom.map_multiset_sum {α : Type u_2} {β : Type u_3} [AddCommMonoid α] [AddCommMonoid β] (f : α →+ β) (s : Multiset α) :
        theorem MonoidHom.map_multiset_prod {α : Type u_2} {β : Type u_3} [CommMonoid α] [CommMonoid β] (f : α →* β) (s : Multiset α) :