Theorem: MvPowerSeries.trunc_one
File: Mathlib/RingTheory/MvPowerSeries/Trunc.lean

tactic: rw [coeff_trunc, coeff_one]
state_before: σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
⊢ MvPolynomial.coeff m ((trunc R n) 1) = MvPolynomial.coeff m 1
state_after: σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
⊢ (if m < n then if m = 0 then 1 else 0 else 0) = MvPolynomial.coeff m 1

tactic: split_ifs with H H'
state_before: σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
⊢ (if m < n then if m = 0 then 1 else 0 else 0) = MvPolynomial.coeff m 1
state_after: case pos
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : m < n
H' : m = 0
⊢ 1 = MvPolynomial.coeff m 1

case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : m < n
H' : ¬m = 0
⊢ 0 = MvPolynomial.coeff m 1

case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : ¬m < n
⊢ 0 = MvPolynomial.coeff m 1

tactic: subst m
state_before: case pos
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : m < n
H' : m = 0
⊢ 1 = MvPolynomial.coeff m 1
state_after: case pos
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
H : 0 < n
⊢ 1 = MvPolynomial.coeff 0 1

tactic: simp
state_before: case pos
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
H : 0 < n
⊢ 1 = MvPolynomial.coeff 0 1
state_after: no goals

tactic: symm
state_before: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : m < n
H' : ¬m = 0
⊢ 0 = MvPolynomial.coeff m 1
state_after: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : m < n
H' : ¬m = 0
⊢ MvPolynomial.coeff m 1 = 0

tactic: rw [MvPolynomial.coeff_one]
state_before: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : m < n
H' : ¬m = 0
⊢ MvPolynomial.coeff m 1 = 0
state_after: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : m < n
H' : ¬m = 0
⊢ (if 0 = m then 1 else 0) = 0

tactic: exact if_neg (Ne.symm H')
state_before: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : m < n
H' : ¬m = 0
⊢ (if 0 = m then 1 else 0) = 0
state_after: no goals

tactic: symm
state_before: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : ¬m < n
⊢ 0 = MvPolynomial.coeff m 1
state_after: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : ¬m < n
⊢ MvPolynomial.coeff m 1 = 0

tactic: rw [MvPolynomial.coeff_one]
state_before: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : ¬m < n
⊢ MvPolynomial.coeff m 1 = 0
state_after: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : ¬m < n
⊢ (if 0 = m then 1 else 0) = 0

tactic: refine if_neg ?_
state_before: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : ¬m < n
⊢ (if 0 = m then 1 else 0) = 0
state_after: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : ¬m < n
⊢ ¬0 = m

tactic: rintro rfl
state_before: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
m : σ →₀ ℕ
H : ¬m < n
⊢ ¬0 = m
state_after: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
H : ¬0 < n
⊢ False

tactic: apply H
state_before: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
H : ¬0 < n
⊢ False
state_after: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
H : ¬0 < n
⊢ 0 < n

tactic: exact Ne.bot_lt hnn
state_before: case neg
σ : Type u_1
R : Type u_2
inst✝ : CommSemiring R
n✝ n : σ →₀ ℕ
hnn : n ≠ 0
H : ¬0 < n
⊢ 0 < n
state_after: no goals