Theorem: DividedPowerAlgebra.lift'_imp
Proof state before:
case zero
R : Type u_1
M : Type u_2
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_3
inst✝¹ : CommSemiring A
inst✝ : Algebra R A
f : ℕ × M → A
hf_zero : ∀ (m : M), f (0, m) = 1
hf_smul : ∀ (n : ℕ) (r : R) (m : M), f (n, r • m) = r ^ n • f (n, m)
hf_mul : ∀ (n p : ℕ) (m : M), f (n, m) * f (p, m) = (n + p).choose n • f (n + p, m)
hf_add :
  ∀ (n : ℕ) (u v : M),
    f (n, u + v) =
      ∑ x ∈ antidiagonal n,
        match x with
        | (k, l) => f (k, u) * f (l, v)
a : M
⊢ f (0, a) = 1

case smul
R : Type u_1
M : Type u_2
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_3
inst✝¹ : CommSemiring A
inst✝ : Algebra R A
f : ℕ × M → A
hf_zero : ∀ (m : M), f (0, m) = 1
hf_smul : ∀ (n : ℕ) (r : R) (m : M), f (n, r • m) = r ^ n • f (n, m)
hf_mul : ∀ (n p : ℕ) (m : M), f (n, m) * f (p, m) = (n + p).choose n • f (n + p, m)
hf_add :
  ∀ (n : ℕ) (u v : M),
    f (n, u + v) =
      ∑ x ∈ antidiagonal n,
        match x with
        | (k, l) => f (k, u) * f (l, v)
r : R
n : ℕ
a : M
⊢ f (n, r • a) = r ^ n • f (n, a)

case mul
R : Type u_1
M : Type u_2
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_3
inst✝¹ : CommSemiring A
inst✝ : Algebra R A
f : ℕ × M → A
hf_zero : ∀ (m : M), f (0, m) = 1
hf_smul : ∀ (n : ℕ) (r : R) (m : M), f (n, r • m) = r ^ n • f (n, m)
hf_mul : ∀ (n p : ℕ) (m : M), f (n, m) * f (p, m) = (n + p).choose n • f (n + p, m)
hf_add :
  ∀ (n : ℕ) (u v : M),
    f (n, u + v) =
      ∑ x ∈ antidiagonal n,
        match x with
        | (k, l) => f (k, u) * f (l, v)
m n : ℕ
a : M
⊢ f (m, a) * f (n, a) = (m + n).choose m • f (m + n, a)

case add
R : Type u_1
M : Type u_2
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_3
inst✝¹ : CommSemiring A
inst✝ : Algebra R A
f : ℕ × M → A
hf_zero : ∀ (m : M), f (0, m) = 1
hf_smul : ∀ (n : ℕ) (r : R) (m : M), f (n, r • m) = r ^ n • f (n, m)
hf_mul : ∀ (n p : ℕ) (m : M), f (n, m) * f (p, m) = (n + p).choose n • f (n + p, m)
hf_add :
  ∀ (n : ℕ) (u v : M),
    f (n, u + v) =
      ∑ x ∈ antidiagonal n,
        match x with
        | (k, l) => f (k, u) * f (l, v)
n : ℕ
a b : M
⊢ f (n, a + b) = ∑ x ∈ antidiagonal n, f (x.1, a) * f (x.2, b)
Tactic:
. apply hf_zero
Proof state after:
case smul
R : Type u_1
M : Type u_2
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_3
inst✝¹ : CommSemiring A
inst✝ : Algebra R A
f : ℕ × M → A
hf_zero : ∀ (m : M), f (0, m) = 1
hf_smul : ∀ (n : ℕ) (r : R) (m : M), f (n, r • m) = r ^ n • f (n, m)
hf_mul : ∀ (n p : ℕ) (m : M), f (n, m) * f (p, m) = (n + p).choose n • f (n + p, m)
hf_add :
  ∀ (n : ℕ) (u v : M),
    f (n, u + v) =
      ∑ x ∈ antidiagonal n,
        match x with
        | (k, l) => f (k, u) * f (l, v)
r : R
n : ℕ
a : M
⊢ f (n, r • a) = r ^ n • f (n, a)

case mul
R : Type u_1
M : Type u_2
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_3
inst✝¹ : CommSemiring A
inst✝ : Algebra R A
f : ℕ × M → A
hf_zero : ∀ (m : M), f (0, m) = 1
hf_smul : ∀ (n : ℕ) (r : R) (m : M), f (n, r • m) = r ^ n • f (n, m)
hf_mul : ∀ (n p : ℕ) (m : M), f (n, m) * f (p, m) = (n + p).choose n • f (n + p, m)
hf_add :
  ∀ (n : ℕ) (u v : M),
    f (n, u + v) =
      ∑ x ∈ antidiagonal n,
        match x with
        | (k, l) => f (k, u) * f (l, v)
m n : ℕ
a : M
⊢ f (m, a) * f (n, a) = (m + n).choose m • f (m + n, a)

case add
R : Type u_1
M : Type u_2
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_3
inst✝¹ : CommSemiring A
inst✝ : Algebra R A
f : ℕ × M → A
hf_zero : ∀ (m : M), f (0, m) = 1
hf_smul : ∀ (n : ℕ) (r : R) (m : M), f (n, r • m) = r ^ n • f (n, m)
hf_mul : ∀ (n p : ℕ) (m : M), f (n, m) * f (p, m) = (n + p).choose n • f (n + p, m)
hf_add :
  ∀ (n : ℕ) (u v : M),
    f (n, u + v) =
      ∑ x ∈ antidiagonal n,
        match x with
        | (k, l) => f (k, u) * f (l, v)
n : ℕ
a b : M
⊢ f (n, a + b) = ∑ x ∈ antidiagonal n, f (x.1, a) * f (x.2, b)