Theorem: DividedPowers.IdealAdd.dpow_comp_aux
Proof state before:
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
L1 :
  ∀ (k : Sym ℕ m),
    ∀ i ∈ range (n + 1),
      dpow hI hJ (Multiset.count i ↑k) (hI.dpow i a * hJ.dpow (n - i) b) =
        ↑(DividedPowers.IdealAdd.cnik n i ↑k) * hI.dpow (Multiset.count i ↑k * i) a *
          hJ.dpow (Multiset.count i ↑k * (n - i)) b
⊢ ∑ k ∈ (range (n + 1)).sym m, ∏ i ∈ range (n + 1), dpow hI hJ (Multiset.count i ↑k) (hI.dpow i a * hJ.dpow (n - i) b) =
    ∑ p ∈ range (m * n + 1),
      ↑(∑ x ∈ filter (fun l => ∑ i ∈ range (n + 1), Multiset.count i ↑l * i = p) ((range (n + 1)).sym m),
              ((∏ i ∈ range (n + 1), DividedPowers.IdealAdd.cnik n i ↑x) *
                  Nat.multinomial (range (n + 1)) fun i => Multiset.count i ↑x * i) *
                Nat.multinomial (range (n + 1)) fun i => Multiset.count i ↑x * (n - i)) *
          hI.dpow p a *
        hJ.dpow (m * n - p) b

case dpow_zero
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ ∀ {x : A}, x ∈ ?m.65386 → dpow hI hJ 0 x = 1

case dpow_add
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ ∀ (n : ℕ) {x y : A},
    x ∈ ?m.65386 → y ∈ ?m.65386 → dpow hI hJ n (x + y) = ∑ k ∈ antidiagonal n, dpow hI hJ k.1 x * dpow hI hJ k.2 y

case dpow_eval_zero
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ ∀ {n : ℕ}, n ≠ 0 → dpow hI hJ n 0 = 0

case hx
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ ∀ i ∈ range (n + 1), hI.dpow i a * hJ.dpow (n - i) b ∈ ?m.65386

A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ Ideal A
Tactic:
set φ : Sym ℕ m → ℕ := fun k => (Finset.range (n + 1)).sum fun i => Multiset.count i ↑k * i
  with hφ_def
Proof state after:
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
L1 :
  ∀ (k : Sym ℕ m),
    ∀ i ∈ range (n + 1),
      dpow hI hJ (Multiset.count i ↑k) (hI.dpow i a * hJ.dpow (n - i) b) =
        ↑(DividedPowers.IdealAdd.cnik n i ↑k) * hI.dpow (Multiset.count i ↑k * i) a *
          hJ.dpow (Multiset.count i ↑k * (n - i)) b
φ : Sym ℕ m → ℕ := fun k => ∑ i ∈ range (n + 1), Multiset.count i ↑k * i
hφ_def : φ = fun k => ∑ i ∈ range (n + 1), Multiset.count i ↑k * i
⊢ ∑ k ∈ (range (n + 1)).sym m, ∏ i ∈ range (n + 1), dpow hI hJ (Multiset.count i ↑k) (hI.dpow i a * hJ.dpow (n - i) b) =
    ∑ p ∈ range (m * n + 1),
      ↑(∑ x ∈ filter (fun l => ∑ i ∈ range (n + 1), Multiset.count i ↑l * i = p) ((range (n + 1)).sym m),
              ((∏ i ∈ range (n + 1), DividedPowers.IdealAdd.cnik n i ↑x) *
                  Nat.multinomial (range (n + 1)) fun i => Multiset.count i ↑x * i) *
                Nat.multinomial (range (n + 1)) fun i => Multiset.count i ↑x * (n - i)) *
          hI.dpow p a *
        hJ.dpow (m * n - p) b

case dpow_zero
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ ∀ {x : A}, x ∈ ?m.65386 → dpow hI hJ 0 x = 1

case dpow_add
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ ∀ (n : ℕ) {x y : A},
    x ∈ ?m.65386 → y ∈ ?m.65386 → dpow hI hJ n (x + y) = ∑ k ∈ antidiagonal n, dpow hI hJ k.1 x * dpow hI hJ k.2 y

case dpow_eval_zero
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ ∀ {n : ℕ}, n ≠ 0 → dpow hI hJ n 0 = 0

case hx
A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ ∀ i ∈ range (n + 1), hI.dpow i a * hJ.dpow (n - i) b ∈ ?m.65386

A : Type u_1
inst✝ : CommRing A
I : Ideal A
hI : DividedPowers I
J : Ideal A
hJ : DividedPowers J
hIJ : ∀ (n : ℕ), ∀ a ∈ I ⊓ J, hI.dpow n a = hJ.dpow n a
m n : ℕ
hn : n ≠ 0
a : A
ha : a ∈ I
b : A
hb : b ∈ J
⊢ Ideal A