Module: Mathlib.RingTheory.DividedPowerAlgebra.Init

Goal state before:
pp: R : Type u_2
M : Type u_3
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_4
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)
p q : MvPolynomial (ℕ × M) R
h : Rel R M p q
⊢ (eval₂AlgHom R f) p = (eval₂AlgHom R f) q

Tactic:
rcases h

Goal state after:
case rfl_zero
R : Type u_2
M : Type u_3
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_4
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)
⊢ (eval₂AlgHom R f) 0 = (eval₂AlgHom R f) 0

case zero
R : Type u_2
M : Type u_3
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_4
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
⊢ (eval₂AlgHom R f) (X (0, a✝)) = (eval₂AlgHom R f) 1

case smul
R : Type u_2
M : Type u_3
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_4
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
⊢ (eval₂AlgHom R f) (X (n✝, r✝ • a✝)) = (eval₂AlgHom R f) (r✝ ^ n✝ • X (n✝, a✝))

case mul
R : Type u_2
M : Type u_3
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_4
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
⊢ (eval₂AlgHom R f) (X (m✝, a✝) * X (n✝, a✝)) = (eval₂AlgHom R f) ((m✝ + n✝).choose m✝ • X (m✝ + n✝, a✝))

case add
R : Type u_2
M : Type u_3
inst✝⁴ : CommSemiring R
inst✝³ : AddCommMonoid M
inst✝² : Module R M
A : Type u_4
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
⊢ (eval₂AlgHom R f) (X (n✝, a✝ + b✝)) = (eval₂AlgHom R f) (∑ k ∈ antidiagonal n✝, X (k.1, a✝) * X (k.2, b✝))