mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.LinearAlgebra.RootSystem.CartanMatrix

Goal state before:
pp: ι : Type u_1
R : Type u_2
M : Type u_3
N : Type u_4
inst✝¹⁰ : CommRing R
inst✝⁹ : AddCommGroup M
inst✝⁸ : Module R M
inst✝⁷ : AddCommGroup N
inst✝⁶ : Module R N
P : RootPairing ι R M N
b : P.Base
inst✝⁵ : P.IsCrystallographic
inst✝⁴ : CharZero R
inst✝³ : IsDomain R
inst✝² : Finite ι
inst✝¹ : DecidableEq ι
inst✝ : P.IsRootSystem
⊢ ¬HasEigenvalue (toLin' b.cartanMatrix) 4

Tactic:
obtain ⟨d, hd, hdS⟩ := b.exists_cartanMatrix_diagaonal_mul_posDef

Goal state after:
ι : Type u_1
R : Type u_2
M : Type u_3
N : Type u_4
inst✝¹⁰ : CommRing R
inst✝⁹ : AddCommGroup M
inst✝⁸ : Module R M
inst✝⁷ : AddCommGroup N
inst✝⁶ : Module R N
P : RootPairing ι R M N
b : P.Base
inst✝⁵ : P.IsCrystallographic
inst✝⁴ : CharZero R
inst✝³ : IsDomain R
inst✝² : Finite ι
inst✝¹ : DecidableEq ι
inst✝ : P.IsRootSystem
d : ↥b.support → ℤ
hd : ∀ (i : ↥b.support), 0 < d i
hdS : (Matrix.diagonal d * b.cartanMatrix).PosDef
⊢ ¬HasEigenvalue (toLin' b.cartanMatrix) 4
Module: Mathlib.RingTheory.Polynomial.Pochhammer

Goal state before:
pp: S : Type u
inst✝ : Semiring S
n : ℕ
⊢ ascPochhammer S (n + 1) = ascPochhammer S n * (X + ↑n)

Tactic:
by
  suffices h : ascPochhammer ℕ (n + 1) = ascPochhammer ℕ n * (X + (n : ℕ[X])) by
    apply_fun Polynomial.map (algebraMap ℕ S) at h
    simpa only [ascPochhammer_map, Polynomial.map_mul, Polynomial.map_add, map_X,
      Polynomial.map_natCast] using h
  induction n with
  | zero => simp
  | succ n ih =>
    conv_lhs =>
      rw [ascPochhammer_succ_left, ih, mul_comp, ← mul_assoc, ← ascPochhammer_succ_left, add_comp,
          X_comp, natCast_comp, add_assoc, add_comm (1 : ℕ[X]), ← Nat.cast_succ]

Goal state after:
Module: Mathlib.LinearAlgebra.Lagrange

Goal state before:
pp: F : Type u_1
inst✝ : Field F
x y : F
⊢ ¬basisDivisor x y = 0 ↔ x ≠ y

Tactic:
basisDivisor_eq_zero_iff

Goal state after:
F : Type u_1
inst✝ : Field F
x y : F
⊢ ¬x = y ↔ x ≠ y
Module: Mathlib.LinearAlgebra.Lagrange

Goal state before:
pp: F : Type u_1
inst✝¹ : Field F
ι : Type u_2
inst✝ : DecidableEq ι
s : Finset ι
v : ι → F
i : ι
hvs : Set.InjOn v ↑s
hi : i ∈ s
⊢ ∀ (j : ι), j ≠ i ∧ j ∈ s → ¬basisDivisor (v i) (v j) = 0

Tactic:
basisDivisor_eq_zero_iff

Goal state after:
F : Type u_1
inst✝¹ : Field F
ι : Type u_2
inst✝ : DecidableEq ι
s : Finset ι
v : ι → F
i : ι
hvs : Set.InjOn v ↑s
hi : i ∈ s
⊢ ∀ (j : ι), j ≠ i ∧ j ∈ s → ¬v i = v j
Module: Mathlib.LinearAlgebra.Vandermonde

Goal state before:
pp: K : Type u_2
inst✝ : Field K
n✝ n : ℕ
ih : ∀ (v w : Fin n → K), (projVandermonde v w).det = ∏ i, ∏ j > i, (v j * w i - v i * w j)
v w : Fin (n + 1) → K
h0 : w 0 ≠ 0
r : K := v 0 / w 0
hr : r = v 0 / w 0
W : Matrix (Fin (n + 1)) (Fin (n + 1)) K :=
  of fun i ↦
    Fin.cons (projVandermonde v w i 0) fun j ↦ projVandermonde v w i j.succ - r * projVandermonde v w i j.castSucc
hW_eq : W.submatrix succ succ = of fun i j ↦ (v i.succ - r * w i.succ) * projVandermonde (v ∘ succ) (w ∘ succ) i j
⊢ (-1) ^ ↑0 * W 0 0 *
      ((∏ i, (v i.succ - r * w i.succ)) * ∏ i, ∏ j > i, ((v ∘ succ) j * (w ∘ succ) i - (v ∘ succ) i * (w ∘ succ) j)) =
    ∏ i, ∏ j > i, (v j * w i - v i * w j)

Tactic:
simp only [Nat.succ_eq_add_one, coe_ofNat_eq_mod, Nat.zero_mod,
      pow_zero, show W 0 0 = w 0 ^ n by simp [W, projVandermonde_apply], one_mul, hr]

Goal state after:
K : Type u_2
inst✝ : Field K
n✝ n : ℕ
ih : ∀ (v w : Fin n → K), (projVandermonde v w).det = ∏ i, ∏ j > i, (v j * w i - v i * w j)
v w : Fin (n + 1) → K
h0 : w 0 ≠ 0
r : K := v 0 / w 0
hr : r = v 0 / w 0
W : Matrix (Fin (n + 1)) (Fin (n + 1)) K :=
  of fun i ↦
    Fin.cons (projVandermonde v w i 0) fun j ↦ projVandermonde v w i j.succ - r * projVandermonde v w i j.castSucc
hW_eq : W.submatrix succ succ = of fun i j ↦ (v i.succ - r * w i.succ) * projVandermonde (v ∘ succ) (w ∘ succ) i j
⊢ w 0 ^ n *
      ((∏ x, (v x.succ - v 0 / w 0 * w x.succ)) *
        ∏ i, ∏ j > i, ((v ∘ succ) j * (w ∘ succ) i - (v ∘ succ) i * (w ∘ succ) j)) =
    ∏ i, ∏ j > i, (v j * w i - v i * w j)
Module: Mathlib.Algebra.Lie.Basis.Prod

Goal state before:
pp: ι₁ : Type u_1
ι₂ : Type u_2
L₁ : Type u_3
L₂ : Type u_4
inst✝⁶ : Finite ι₁
inst✝⁵ : Finite ι₂
eι : ι₁ ≃ ι₂
inst✝⁴ : LieRing L₁
inst✝³ : LieRing L₂
R : Type u_5
inst✝² : CommRing R
inst✝¹ : LieAlgebra R L₁
H₁ : LieSubalgebra R L₁
b₁ : Basis ι₁ H₁
inst✝ : LieAlgebra R L₂
H₂ : LieSubalgebra R L₂
b₂ : Basis ι₂ H₂
⊢ range (prodH eι b₁ b₂) ⊆ ↑(lieSpan R (↥(prod eι b₁ b₂)) (range (prodE eι b₁ b₂) ∪ range (prodF eι b₁ b₂)))

Tactic:
rintro - ⟨i, rfl⟩

Goal state after:
ι₁ : Type u_1
ι₂ : Type u_2
L₁ : Type u_3
L₂ : Type u_4
inst✝⁶ : Finite ι₁
inst✝⁵ : Finite ι₂
eι : ι₁ ≃ ι₂
inst✝⁴ : LieRing L₁
inst✝³ : LieRing L₂
R : Type u_5
inst✝² : CommRing R
inst✝¹ : LieAlgebra R L₁
H₁ : LieSubalgebra R L₁
b₁ : Basis ι₁ H₁
inst✝ : LieAlgebra R L₂
H₂ : LieSubalgebra R L₂
b₂ : Basis ι₂ H₂
i : ι₁
⊢ prodH eι b₁ b₂ i ∈ ↑(lieSpan R (↥(prod eι b₁ b₂)) (range (prodE eι b₁ b₂) ∪ range (prodF eι b₁ b₂)))
Module: Mathlib.LinearAlgebra.Lagrange

Goal state before:
pp: case refine_1
F : Type u_1
inst✝¹ : Field F
ι : Type u_2
inst✝ : DecidableEq ι
s t : Finset ι
v r : ι → F
hvt : Set.InjOn v ↑t
hs✝ : s.Nonempty
hst : s ⊆ t
i : ι
hi : i ∈ s
hs : 1 ≤ #s
hst' : #s ≤ #t
H : #t = 1 + (#t - #s) + (#s - 1)
⊢ ((interpolate (insert i (t \ s)) v) r).degree + ↑(#s - 1) < ↑(#t)

Tactic:
H,

Goal state after:
case refine_1
F : Type u_1
inst✝¹ : Field F
ι : Type u_2
inst✝ : DecidableEq ι
s t : Finset ι
v r : ι → F
hvt : Set.InjOn v ↑t
hs✝ : s.Nonempty
hst : s ⊆ t
i : ι
hi : i ∈ s
hs : 1 ≤ #s
hst' : #s ≤ #t
H : #t = 1 + (#t - #s) + (#s - 1)
⊢ ((interpolate (insert i (t \ s)) v) r).degree + ↑(#s - 1) < ↑(1 + (#t - #s) + (#s - 1))
Module: Mathlib.LinearAlgebra.Lagrange

Goal state before:
pp: case pos
F : Type u_1
inst✝¹ : Field F
ι : Type u_2
inst✝ : DecidableEq ι
s t : Finset ι
v r : ι → F
hvt : Set.InjOn v ↑t
hs : s.Nonempty
hst : s ⊆ t
i : ι
hi : i ∈ t
hi' : i ∈ s
⊢ ∑ x ∈ s, eval (v i) ((interpolate (insert x (t \ s)) v) r) * eval (v i) (Lagrange.basis s v x) = r i

pp: case neg
F : Type u_1
inst✝¹ : Field F
ι : Type u_2
inst✝ : DecidableEq ι
s t : Finset ι
v r : ι → F
hvt : Set.InjOn v ↑t
hs : s.Nonempty
hst : s ⊆ t
i : ι
hi : i ∈ t
hi' : i ∉ s
⊢ ∑ x ∈ s, eval (v i) ((interpolate (insert x (t \ s)) v) r) * eval (v i) (Lagrange.basis s v x) = r i

Tactic:
· rw [← add_sum_erase _ _ hi', eval_basis_self (hvt.mono hst) hi',
        eval_interpolate_at_node _
          (hvt.mono (coe_subset.mpr (insert_subset_iff.mpr ⟨hi, sdiff_subset⟩)))
          (mem_insert_self _ _),
        mul_one, add_eq_left]
      refine sum_eq_zero fun j hj => ?_
      rcases mem_erase.mp hj with ⟨hij, _⟩
      rw [eval_basis_of_ne hij hi', mul_zero]

Goal state after:
case neg
F : Type u_1
inst✝¹ : Field F
ι : Type u_2
inst✝ : DecidableEq ι
s t : Finset ι
v r : ι → F
hvt : Set.InjOn v ↑t
hs : s.Nonempty
hst : s ⊆ t
i : ι
hi : i ∈ t
hi' : i ∉ s
⊢ ∑ x ∈ s, eval (v i) ((interpolate (insert x (t \ s)) v) r) * eval (v i) (Lagrange.basis s v x) = r i
Module: Mathlib.LinearAlgebra.Lagrange

Goal state before:
pp: F : Type u_1
inst✝¹ : Field F
ι : Type u_3
inst✝ : Finite ι
x y : ι → F
hwd : ∀ (i j : ι), x i = x j → y i = y j
this : Fintype ι
hinj : Set.InjOn (fun d ↦ d) ↑(image x univ)
v : F → F := fun z ↦ if h : ∃ i, x i = z then y h.choose else 0
v_def : v = fun z ↦ if h : ∃ i, x i = z then y h.choose else 0
i : ι
⊢ (if h : ∃ i_1, x i_1 = x i then y h.choose else 0) = y i

Tactic:
split_ifs with h

Goal state after:
case pos
F : Type u_1
inst✝¹ : Field F
ι : Type u_3
inst✝ : Finite ι
x y : ι → F
hwd : ∀ (i j : ι), x i = x j → y i = y j
this : Fintype ι
hinj : Set.InjOn (fun d ↦ d) ↑(image x univ)
v : F → F := fun z ↦ if h : ∃ i, x i = z then y h.choose else 0
v_def : v = fun z ↦ if h : ∃ i, x i = z then y h.choose else 0
i : ι
h : ∃ i_1, x i_1 = x i
⊢ y h.choose = y i

case neg
F : Type u_1
inst✝¹ : Field F
ι : Type u_3
inst✝ : Finite ι
x y : ι → F
hwd : ∀ (i j : ι), x i = x j → y i = y j
this : Fintype ι
hinj : Set.InjOn (fun d ↦ d) ↑(image x univ)
v : F → F := fun z ↦ if h : ∃ i, x i = z then y h.choose else 0
v_def : v = fun z ↦ if h : ∃ i, x i = z then y h.choose else 0
i : ι
h : ¬∃ i_1, x i_1 = x i
⊢ 0 = y i
Module: Mathlib.LinearAlgebra.Lagrange

Goal state before:
pp: F : Type u_1
inst✝¹ : Field F
ι : Type u_2
inst✝ : DecidableEq ι
s : Finset ι
v : ι → F
i : ι
x : F
hi : i ∈ s
hxi : x ≠ v i
⊢ eval x (Lagrange.basis s v i) = eval x (nodal s v) * (nodalWeight s v i * (x - v i)⁻¹)

Tactic:
rw [mul_comm, basis_eq_prod_sub_inv_mul_nodal_div hi, eval_mul, eval_C, ←
    nodal_erase_eq_nodal_div hi, eval_nodal, eval_nodal, mul_assoc, ← mul_prod_erase _ _ hi, ←
    mul_assoc (x - v i)⁻¹, inv_mul_cancel₀ (sub_ne_zero_of_ne hxi), one_mul]

Goal state after:
Module: Mathlib.LinearAlgebra.Lagrange

Goal state before:
pp: F : Type u_1
inst✝¹ : Field F
ι : Type u_2
inst✝ : DecidableEq ι
s : Finset ι
v : ι → F
x : F
hvs : Set.InjOn v ↑s
hx : ∀ i ∈ s, x ≠ v i
hs : s.Nonempty
⊢ eval x (nodal s v) * ∑ i ∈ s, nodalWeight s v i * (x - v i)⁻¹ = 1

Tactic:
by
    simpa only [Pi.one_apply, interpolate_one hvs hs, eval_one, mul_one] using
      (eval_interpolate_not_at_node 1 hx).symm

Goal state after:
Module: Mathlib.RingTheory.MvPolynomial.WeightedHomogeneous

Goal state before:
pp: R : Type u_1
M : Type u_2
inst✝² : CommSemiring R
σ : Type u_3
inst✝¹ : AddCommMonoid M
w : σ → M
n : M
φ : MvPolynomial σ R
inst✝ : DecidableEq M
⊢ (weightedHomogeneousComponent w n) φ = ∑ d ∈ φ.support with (weight w) d = n, (monomial d) (coeff d φ)

Tactic:
simp [weightedHomogeneousComponent, MvPolynomial, coeff, Finsupp.filter_eq_sum, support, monomial]

Goal state after:
R : Type u_1
M : Type u_2
inst✝² : CommSemiring R
σ : Type u_3
inst✝¹ : AddCommMonoid M
w : σ → M
n : M
φ : MvPolynomial σ R
inst✝ : DecidableEq M
⊢ ∑ x ∈ φ.coeff.support with (weight w) x = n, AddMonoidAlgebra.single x (φ.coeff x) =
    ∑ x ∈ φ.coeff.support with (weight w) x = n, AddMonoidAlgebra.single x (φ.coeff x)
Module: Mathlib.RingTheory.GradedAlgebra.Homogeneous.Ideal

Goal state before:
pp: ι : Type u_1
σ : Type u_2
A : Type u_3
inst✝⁵ : Semiring A
inst✝⁴ : DecidableEq ι
inst✝³ : AddMonoid ι
inst✝² : SetLike σ A
inst✝¹ : AddSubmonoidClass σ A
𝒜 : ι → σ
inst✝ : GradedRing 𝒜
I : Ideal A
h : IsHomogeneous 𝒜 I
⊢ (homogeneousHull 𝒜 I).toIdeal = I

Tactic:
by
  apply le_antisymm _ (Ideal.le_toIdeal_homogeneousHull _ _)
  apply Ideal.span_le.2
  rintro _ ⟨i, x, rfl⟩
  exact h _ x.prop

Goal state after:
Module: Mathlib.RingTheory.MvPolynomial.WeightedHomogeneous

Goal state before:
pp: R : Type u_1
M : Type u_2
inst✝² : CommSemiring R
σ : Type u_3
w : σ → M
inst✝¹ : AddCommMonoid M
inst✝ : DecidableEq M
φ : MvPolynomial σ R
m : M
⊢ ↑((decompose' R w φ) m) = (weightedHomogeneousComponent w m) φ

Tactic:
by
  rw [decompose']
  by_cases hm : m ∈ Finset.image (weight w) φ.support
  · simp only [DirectSum.mk_apply_of_mem hm, Subtype.coe_mk]
  · rw [DirectSum.mk_apply_of_notMem hm, Submodule.coe_zero,
      weightedHomogeneousComponent_eq_zero_of_notMem w φ m hm]

Goal state after:
Module: Mathlib.LinearAlgebra.Eigenspace.Zero

Goal state before:
pp: K : Type u_2
M : Type u_3
inst✝³ : Field K
inst✝² : AddCommGroup M
inst✝¹ : Module K M
inst✝ : Module.Finite K M
φ : End K M
V : Submodule K M := φ.maxGenEigenspace 0
hV : V = ⨆ n, ker (φ ^ n)
W : Submodule K M := ⨅ n, range (φ ^ n)
hVW : IsCompl V W
hφV : ∀ x ∈ V, φ x ∈ V
hφW : ∀ x ∈ W, φ x ∈ W
F : ↥V →ₗ[K] ↥V := restrict φ hφV
G : ↥W →ₗ[K] ↥W := restrict φ hφW
ψ : ↥V × ↥W →ₗ[K] ↥V × ↥W := F.prodMap G
e : (↥V × ↥W) ≃ₗ[K] M := V.prodEquivOfIsCompl W hVW
bV : Basis (ChooseBasisIndex K ↥V) K ↥V := chooseBasis K ↥V
bW : Basis (ChooseBasisIndex K ↥W) K ↥W := chooseBasis K ↥W
b : Basis (ChooseBasisIndex K ↥V ⊕ ChooseBasisIndex K ↥W) K (↥V × ↥W) := bV.prod bW
hψ : ψ = e.symm.conj φ
⊢ finrank K ↥V = (charpoly φ).natTrailingDegree

Tactic:
rw [← e.symm.charpoly_conj φ, ← hψ, charpoly_prodMap,
    natTrailingDegree_mul (charpoly_monic _).ne_zero (charpoly_monic _).ne_zero]

Goal state after:
K : Type u_2
M : Type u_3
inst✝³ : Field K
inst✝² : AddCommGroup M
inst✝¹ : Module K M
inst✝ : Module.Finite K M
φ : End K M
V : Submodule K M := φ.maxGenEigenspace 0
hV : V = ⨆ n, ker (φ ^ n)
W : Submodule K M := ⨅ n, range (φ ^ n)
hVW : IsCompl V W
hφV : ∀ x ∈ V, φ x ∈ V
hφW : ∀ x ∈ W, φ x ∈ W
F : ↥V →ₗ[K] ↥V := restrict φ hφV
G : ↥W →ₗ[K] ↥W := restrict φ hφW
ψ : ↥V × ↥W →ₗ[K] ↥V × ↥W := F.prodMap G
e : (↥V × ↥W) ≃ₗ[K] M := V.prodEquivOfIsCompl W hVW
bV : Basis (ChooseBasisIndex K ↥V) K ↥V := chooseBasis K ↥V
bW : Basis (ChooseBasisIndex K ↥W) K ↥W := chooseBasis K ↥W
b : Basis (ChooseBasisIndex K ↥V ⊕ ChooseBasisIndex K ↥W) K (↥V × ↥W) := bV.prod bW
hψ : ψ = e.symm.conj φ
⊢ finrank K ↥V = F.charpoly.natTrailingDegree + G.charpoly.natTrailingDegree
Module: Mathlib.Algebra.Module.LinearMap.Polynomial

Goal state before:
pp: R : Type u_1
L : Type u_2
M : Type u_3
ι : Type u_5
ιM : Type u_7
inst✝¹⁰ : CommRing R
inst✝⁹ : AddCommGroup L
inst✝⁸ : Module R L
inst✝⁷ : AddCommGroup M
inst✝⁶ : Module R M
φ : L →ₗ[R] End R M
inst✝⁵ : Fintype ι
inst✝⁴ : Fintype ιM
inst✝³ : DecidableEq ι
inst✝² : DecidableEq ιM
b : Basis ι R L
bₘ : Basis ιM R M
ιM' : Type u_8
inst✝¹ : Fintype ιM'
inst✝ : DecidableEq ιM'
bₘ' : Basis ιM' R M
f : Polynomial (MvPolynomial ι R) → Polynomial (MvPolynomial ι R) := Polynomial.map (aeval X).toRingHom
⊢ Function.Injective (Polynomial.map (RingHom.id (MvPolynomial ι R)))

Tactic:
exact Polynomial.map_injective (RingHom.id _) Function.injective_id

Goal state after:
Module: Mathlib.LinearAlgebra.Dimension.LinearMap

Goal state before:
pp: K : Type u
V : Type v
V' : Type v'
V'' : Type v''
inst✝⁶ : Semiring K
inst✝⁵ : AddCommMonoid V
inst✝⁴ : Module K V
inst✝³ : AddCommMonoid V'
inst✝² : Module K V'
inst✝¹ : AddCommMonoid V''
inst✝ : Module K V''
g : V →ₗ[K] V'
f : V' →ₗ[K] V''
⊢ Submodule.map f g.range ≤ f.range

Tactic:
exact LinearMap.map_le_range

Goal state after:
Module: Mathlib.Algebra.Lie.SkewAdjoint

Goal state before:
pp: R : Type u
n : Type w
inst✝² : CommRing R
inst✝¹ : Fintype n
J : Matrix n n R
inst✝ : DecidableEq n
P : Matrix n n R
h : Invertible P
A : Matrix n n R
this : (P.lieConj h) A ∈ skewAdjointMatricesSubmodule J ↔ A ∈ skewAdjointMatricesSubmodule (Pᵀ * J * P)
⊢ A ∈ LieSubalgebra.map (P.lieConj h).symm.toLieHom (skewAdjointMatricesLieSubalgebra J) ↔
    A ∈ skewAdjointMatricesLieSubalgebra (Pᵀ * J * P)

Tactic:
by
      simp only [Submodule.mem_map_equiv, LieSubalgebra.mem_map_submodule]
      exact this

Goal state after:
Module: Mathlib.Algebra.Lie.Classical

Goal state before:
pp: n : Type u_1
R : Type u₂
inst✝² : CommRing R
inst✝¹ : DecidableEq n
inst✝ : Fintype n
A : Matrix n n R
⊢ A ∈ so n R ↔ Aᵀ = -A

Tactic:
so,

Goal state after:
n : Type u_1
R : Type u₂
inst✝² : CommRing R
inst✝¹ : DecidableEq n
inst✝ : Fintype n
A : Matrix n n R
⊢ A ∈ skewAdjointMatricesLieSubalgebra 1 ↔ Aᵀ = -A
Module: Mathlib.LinearAlgebra.SymplecticGroup

Goal state before:
pp: l : Type u_1
R : Type u_2
inst✝² : DecidableEq l
inst✝¹ : CommRing R
inst✝ : Fintype l
⊢ J l R * J l R = -1

Tactic:
rw [J, fromBlocks_multiply]

Goal state after:
l : Type u_1
R : Type u_2
inst✝² : DecidableEq l
inst✝¹ : CommRing R
inst✝ : Fintype l
⊢ fromBlocks (0 * 0 + -1 * 1) (0 * -1 + -1 * 0) (1 * 0 + 0 * 1) (1 * -1 + 0 * 0) = -1
Module: Mathlib.LinearAlgebra.SymplecticGroup

Goal state before:
pp: l : Type u_1
R : Type u_2
inst✝² : DecidableEq l
inst✝¹ : CommRing R
inst✝ : Fintype l
a b : Matrix (l ⊕ l) (l ⊕ l) R
ha : a ∈ {A | A * J l R * Aᵀ = J l R}
hb : b ∈ {A | A * J l R * Aᵀ = J l R}
⊢ a * b ∈ {A | A * J l R * Aᵀ = J l R}

Tactic:
by
    simp only [Set.mem_ofPred_eq, transpose_mul] at *
    rw [← Matrix.mul_assoc, a.mul_assoc, a.mul_assoc, hb]
    exact ha

Goal state after:
Module: Mathlib.LinearAlgebra.SymplecticGroup

Goal state before:
pp: l : Type u_1
R : Type u_2
inst✝² : DecidableEq l
inst✝¹ : Fintype l
inst✝ : CommRing R
A : Matrix (l ⊕ l) (l ⊕ l) R
hA : A ∈ symplecticGroup l R
⊢ -J l R * Aᵀ * J l R * A = 1

Tactic:
by simp only [Matrix.neg_mul, inv_left_mul_aux hA]

Goal state after:
Module: Mathlib.LinearAlgebra.SymplecticGroup

Goal state before:
pp: l : Type u_1
R : Type u_2
inst✝³ : DecidableEq l
inst✝² : Fintype l
inst✝¹ : CommRing R
A B C D : Matrix l l R
inst✝ : IsLocalRing R
hA : fromBlocks A B C D ∈ symplecticGroup l R
k : Type u_2 := IsLocalRing.ResidueField R
f : R →+* IsLocalRing.ResidueField R := IsLocalRing.residue R
A' : Matrix l l (IsLocalRing.ResidueField R) := f.mapMatrix A
C' : Matrix l l (IsLocalRing.ResidueField R) := f.mapMatrix C
F' : Matrix (l ⊕ l) (l ⊕ l) (IsLocalRing.ResidueField R) := fromBlocks A' (f.mapMatrix B) C' (f.mapMatrix D)
F'_def : F' = fromBlocks A' (f.mapMatrix B) C' (f.mapMatrix D)
hF' : IsUnit F'
hker : ∀ (x : l → k), A' *ᵥ x = 0 → C' *ᵥ x = 0 → x = 0
⊢ ∃ X, X.IsSymm ∧ IsUnit (A + X * C).det

Tactic:
obtain ⟨Y, hY_symm, hY_det⟩ :=
    exists_symmetric_X_invertible_add_mul_of_ker_inter_eq_bot hker <| by
      change f.mapMatrix Aᵀ * f.mapMatrix C = f.mapMatrix Cᵀ * f.mapMatrix A
      rw [← map_mul, (fromBlocks_mem_iff.1 hA).1, map_mul]

Goal state after:
l : Type u_1
R : Type u_2
inst✝³ : DecidableEq l
inst✝² : Fintype l
inst✝¹ : CommRing R
A B C D : Matrix l l R
inst✝ : IsLocalRing R
hA : fromBlocks A B C D ∈ symplecticGroup l R
k : Type u_2 := IsLocalRing.ResidueField R
f : R →+* IsLocalRing.ResidueField R := IsLocalRing.residue R
A' : Matrix l l (IsLocalRing.ResidueField R) := f.mapMatrix A
C' : Matrix l l (IsLocalRing.ResidueField R) := f.mapMatrix C
F' : Matrix (l ⊕ l) (l ⊕ l) (IsLocalRing.ResidueField R) := fromBlocks A' (f.mapMatrix B) C' (f.mapMatrix D)
F'_def : F' = fromBlocks A' (f.mapMatrix B) C' (f.mapMatrix D)
hF' : IsUnit F'
hker : ∀ (x : l → k), A' *ᵥ x = 0 → C' *ᵥ x = 0 → x = 0
Y : Matrix l l k
hY_symm : Y.IsSymm
hY_det : IsUnit (A' + Y * C')
⊢ ∃ X, X.IsSymm ∧ IsUnit (A + X * C).det
Module: Mathlib.Algebra.MonoidAlgebra.Grading

Goal state before:
pp: M : Type u_1
ι : Type u_2
R : Type u_4
inst✝ : CommSemiring R
f : M → ι
m : M
r : R
x : M
hx : x ∈ (single m r).coeff.support
⊢ f x = f m

Tactic:
rw [Finset.mem_singleton.mp (Finsupp.support_single_subset hx)]

Goal state after:
Module: Mathlib.LinearAlgebra.TensorProduct.Decomposition

Goal state before:
pp: ι : Type u_1
R : Type u_2
M : Type u_3
S : Type u_4
inst✝⁶ : CommSemiring R
inst✝⁵ : AddCommMonoid M
inst✝⁴ : Module R M
ℳ : ι → Submodule R M
inst✝³ : DecidableEq ι
inst✝² : Decomposition ℳ
inst✝¹ : CommSemiring S
inst✝ : Algebra R S
⊢ Decomposition fun i ↦ Submodule.baseChange S (ℳ i)

Tactic:
by
  refine .ofLinearMap _ (lmap (ℳ · |>.toBaseChange S) ∘ₗ
    (directSumRight R S S fun i ↦ ℳ i).toLinearMap ∘ₗ
    ((decomposeLinearEquiv ℳ).baseChange R S)) ?_ ?_
  · simp_rw [← comp_assoc]
    rw [← LinearEquiv.eq_comp_toLinearMap_symm]
    ext
    simp
  · ext : 1
    rw [← LinearMap.cancel_right ((ℳ _).toBaseChange_surjective S)]
    ext : 3
    simp

Goal state after:
Module: Mathlib.Algebra.Lie.LieTheorem

Goal state before:
pp: case inr
R : Type u_1
L : Type u_2
A : Type u_3
V : Type u_4
inst✝¹⁹ : CommRing R
inst✝¹⁸ : IsPrincipalIdealRing R
inst✝¹⁷ : IsDomain R
inst✝¹⁶ : CharZero R
inst✝¹⁵ : LieRing L
inst✝¹⁴ : LieAlgebra R L
inst✝¹³ : LieRing A
inst✝¹² : LieAlgebra R A
inst✝¹¹ : Bracket L A
inst✝¹⁰ : Bracket A L
inst✝⁹ : AddCommGroup V
inst✝⁸ : Module R V
inst✝⁷ : Module.Free R V
inst✝⁶ : Module.Finite R V
inst✝⁵ : LieRingModule L V
inst✝⁴ : LieModule R L V
inst✝³ : LieRingModule A V
inst✝² : LieModule R A V
inst✝¹ : IsLieTower L A V
inst✝ : IsLieTower A L V
χ : A → R
z : L
v : V
hv : ∀ (x : A), ⁅x, v⁆ = χ x • v
a : A
hv' : v ≠ 0
U' : ℕ →o Submodule R V :=
  { toFun := fun n ↦ Submodule.span R {x | ∃ i < n, ((toEnd R L V) z ^ i) v = x}, monotone' := ⋯ }
map_U'_le : ∀ (n : ℕ), Submodule.map ((toEnd R L V) z) (U' n) ≤ U' (n + 1)
n : ℕ
hn :
  ∀ (w : A),
    ∀ a < n + 1, (T χ w) (((toEnd R L V) z ^ a) v) ∈ Submodule.span R {x | ∃ i < n, ((toEnd R L V) z ^ i) v = x}
w : A
hm : n + 1 < n + 1 + 1
H : ∀ (w : A), ⁅w, ((toEnd R L V) z ^ n) v⁆ = (T χ w) (((toEnd R L V) z ^ n) v) + χ w • ((toEnd R L V) z ^ n) v
⊢ -⁅⁅z, w⁆, ((toEnd R L V) z ^ n) v⁆ + ⁅z, ⁅w, ((toEnd R L V) z ^ n) v⁆⁆ - χ w • ⁅z, ((toEnd R L V) z ^ n) v⁆ ∈
    Submodule.span R {x | ∃ i < n + 1, ((toEnd R L V) z ^ i) v = x}

Tactic:
H,

Goal state after:
case inr
R : Type u_1
L : Type u_2
A : Type u_3
V : Type u_4
inst✝¹⁹ : CommRing R
inst✝¹⁸ : IsPrincipalIdealRing R
inst✝¹⁷ : IsDomain R
inst✝¹⁶ : CharZero R
inst✝¹⁵ : LieRing L
inst✝¹⁴ : LieAlgebra R L
inst✝¹³ : LieRing A
inst✝¹² : LieAlgebra R A
inst✝¹¹ : Bracket L A
inst✝¹⁰ : Bracket A L
inst✝⁹ : AddCommGroup V
inst✝⁸ : Module R V
inst✝⁷ : Module.Free R V
inst✝⁶ : Module.Finite R V
inst✝⁵ : LieRingModule L V
inst✝⁴ : LieModule R L V
inst✝³ : LieRingModule A V
inst✝² : LieModule R A V
inst✝¹ : IsLieTower L A V
inst✝ : IsLieTower A L V
χ : A → R
z : L
v : V
hv : ∀ (x : A), ⁅x, v⁆ = χ x • v
a : A
hv' : v ≠ 0
U' : ℕ →o Submodule R V :=
  { toFun := fun n ↦ Submodule.span R {x | ∃ i < n, ((toEnd R L V) z ^ i) v = x}, monotone' := ⋯ }
map_U'_le : ∀ (n : ℕ), Submodule.map ((toEnd R L V) z) (U' n) ≤ U' (n + 1)
n : ℕ
hn :
  ∀ (w : A),
    ∀ a < n + 1, (T χ w) (((toEnd R L V) z ^ a) v) ∈ Submodule.span R {x | ∃ i < n, ((toEnd R L V) z ^ i) v = x}
w : A
hm : n + 1 < n + 1 + 1
H : ∀ (w : A), ⁅w, ((toEnd R L V) z ^ n) v⁆ = (T χ w) (((toEnd R L V) z ^ n) v) + χ w • ((toEnd R L V) z ^ n) v
⊢ -((T χ ⁅z, w⁆) (((toEnd R L V) z ^ n) v) + χ ⁅z, w⁆ • ((toEnd R L V) z ^ n) v) + ⁅z, ⁅w, ((toEnd R L V) z ^ n) v⁆⁆ -
      χ w • ⁅z, ((toEnd R L V) z ^ n) v⁆ ∈
    Submodule.span R {x | ∃ i < n + 1, ((toEnd R L V) z ^ i) v = x}
Module: Mathlib.Algebra.Lie.LieTheorem

Goal state before:
pp: case inr
R : Type u_1
L : Type u_2
A : Type u_3
V : Type u_4
inst✝¹⁹ : CommRing R
inst✝¹⁸ : IsPrincipalIdealRing R
inst✝¹⁷ : IsDomain R
inst✝¹⁶ : CharZero R
inst✝¹⁵ : LieRing L
inst✝¹⁴ : LieAlgebra R L
inst✝¹³ : LieRing A
inst✝¹² : LieAlgebra R A
inst✝¹¹ : Bracket L A
inst✝¹⁰ : Bracket A L
inst✝⁹ : AddCommGroup V
inst✝⁸ : Module R V
inst✝⁷ : Module.Free R V
inst✝⁶ : Module.Finite R V
inst✝⁵ : LieRingModule L V
inst✝⁴ : LieModule R L V
inst✝³ : LieRingModule A V
inst✝² : LieModule R A V
inst✝¹ : IsLieTower L A V
inst✝ : IsLieTower A L V
χ : A → R
z : L
v : V
hv : ∀ (x : A), ⁅x, v⁆ = χ x • v
a : A
hv' : v ≠ 0
U' : ℕ →o Submodule R V :=
  { toFun := fun n ↦ Submodule.span R {x | ∃ i < n, ((toEnd R L V) z ^ i) v = x}, monotone' := ⋯ }
map_U'_le : ∀ (n : ℕ), Submodule.map ((toEnd R L V) z) (U' n) ≤ U' (n + 1)
n : ℕ
hn :
  ∀ (w : A),
    ∀ a < n + 1, (T χ w) (((toEnd R L V) z ^ a) v) ∈ Submodule.span R {x | ∃ i < n, ((toEnd R L V) z ^ i) v = x}
w : A
hm : n + 1 < n + 1 + 1
H : ∀ (w : A), ⁅w, ((toEnd R L V) z ^ n) v⁆ = (T χ w) (((toEnd R L V) z ^ n) v) + χ w • ((toEnd R L V) z ^ n) v
⊢ -((T χ ⁅z, w⁆) (((toEnd R L V) z ^ n) v) + χ ⁅z, w⁆ • ((toEnd R L V) z ^ n) v) + ⁅z, ⁅w, ((toEnd R L V) z ^ n) v⁆⁆ -
      χ w • ⁅z, ((toEnd R L V) z ^ n) v⁆ ∈
    Submodule.span R {x | ∃ i < n + 1, ((toEnd R L V) z ^ i) v = x}

Tactic:
H,

Goal state after:
case inr
R : Type u_1
L : Type u_2
A : Type u_3
V : Type u_4
inst✝¹⁹ : CommRing R
inst✝¹⁸ : IsPrincipalIdealRing R
inst✝¹⁷ : IsDomain R
inst✝¹⁶ : CharZero R
inst✝¹⁵ : LieRing L
inst✝¹⁴ : LieAlgebra R L
inst✝¹³ : LieRing A
inst✝¹² : LieAlgebra R A
inst✝¹¹ : Bracket L A
inst✝¹⁰ : Bracket A L
inst✝⁹ : AddCommGroup V
inst✝⁸ : Module R V
inst✝⁷ : Module.Free R V
inst✝⁶ : Module.Finite R V
inst✝⁵ : LieRingModule L V
inst✝⁴ : LieModule R L V
inst✝³ : LieRingModule A V
inst✝² : LieModule R A V
inst✝¹ : IsLieTower L A V
inst✝ : IsLieTower A L V
χ : A → R
z : L
v : V
hv : ∀ (x : A), ⁅x, v⁆ = χ x • v
a : A
hv' : v ≠ 0
U' : ℕ →o Submodule R V :=
  { toFun := fun n ↦ Submodule.span R {x | ∃ i < n, ((toEnd R L V) z ^ i) v = x}, monotone' := ⋯ }
map_U'_le : ∀ (n : ℕ), Submodule.map ((toEnd R L V) z) (U' n) ≤ U' (n + 1)
n : ℕ
hn :
  ∀ (w : A),
    ∀ a < n + 1, (T χ w) (((toEnd R L V) z ^ a) v) ∈ Submodule.span R {x | ∃ i < n, ((toEnd R L V) z ^ i) v = x}
w : A
hm : n + 1 < n + 1 + 1
H : ∀ (w : A), ⁅w, ((toEnd R L V) z ^ n) v⁆ = (T χ w) (((toEnd R L V) z ^ n) v) + χ w • ((toEnd R L V) z ^ n) v
⊢ -((T χ ⁅z, w⁆) (((toEnd R L V) z ^ n) v) + χ ⁅z, w⁆ • ((toEnd R L V) z ^ n) v) +
        ⁅z, (T χ w) (((toEnd R L V) z ^ n) v) + χ w • ((toEnd R L V) z ^ n) v⁆ -
      χ w • ⁅z, ((toEnd R L V) z ^ n) v⁆ ∈
    Submodule.span R {x | ∃ i < n + 1, ((toEnd R L V) z ^ i) v = x}