mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.AlgebraicGeometry.Morphisms.FlatDescent

Goal state before:
pp: P : MorphismProperty Scheme
inst✝¹ : P.DescendsAlong (@Surjective ⊓ @Flat ⊓ @QuasiCompact)
inst✝ : IsZariskiLocalAtTarget P
⊢ P.DescendsAlong (@Surjective ⊓ @Flat ⊓ @LocallyOfFinitePresentation)

Tactic:
by
  apply IsZariskiLocalAtTarget.descendsAlong
  rintro R X Y f g ⟨⟨h₁, h₂⟩, h₃⟩ H
  obtain ⟨V : X.Opens, hV, e⟩ := f.isOpenMap.exists_opens_image_eq_of_prespectralSpace
    f.continuous (by simp) isOpen_univ isCompact_univ
  refine MorphismProperty.of_isPullback_of_descendsAlong (Q := @Surjective ⊓ @Flat ⊓ @QuasiCompact)
    (.paste_vert (.of_hasPullback V.ι _) (.of_hasPullback f g)) ⟨⟨?_, inferInstance⟩,
      (quasiCompact_iff_compactSpace _).mpr (isCompact_iff_compactSpace.mp hV)⟩ ?_
  · exact ⟨fun x ↦ have ⟨y, hyV, e⟩ := e.ge (Set.mem_univ x); ⟨⟨y, hyV⟩, e⟩⟩
  · exact IsZariskiLocalAtTarget.of_isPullback (.flip <| .of_hasPullback _ _) H

Goal state after:
Module: Mathlib.RingTheory.RingHom.QuasiFinite

Goal state before:
pp: R S : Type u_6
inst✝¹ : CommRing R
inst✝ : CommRing S
f✝ : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
H : ∀ (r : ↥s), (fun {R S} [CommRing R] [CommRing S] ↦ QuasiFinite) ((algebraMap S (Localization.Away ↑r)).comp f✝)
algInst✝ : Algebra R S := f✝.toAlgebra
P : Ideal R
x✝ : P.IsPrime
this✝¹ : ∀ (r : ↥s), Module.Finite P.ResidueField (P.Fiber (Localization.Away ↑r))
φ : (r : ↥s) → P.Fiber S →ₐ[P.ResidueField] P.Fiber (Localization.Away ↑r) :=
  fun r ↦
    Algebra.TensorProduct.map (AlgHom.id P.ResidueField P.ResidueField)
      (IsScalarTower.toAlgHom R S (Localization.Away ↑r))
f : P.Fiber S →ₐ[P.ResidueField] (r : ↥s) → P.Fiber (Localization.Away ↑r) := AlgHom.pi φ
this✝ : IsNoetherian P.ResidueField ((r : ↥s) → P.Fiber (Localization.Away ↑r))
a : P.Fiber S
ha : f a = 0
J : Ideal (P.Fiber S)
hJ : J.IsMaximal
I : ↑(P.primesOver S) := (PrimeSpectrum.primesOverOrderIsoFiber R S P).symm { asIdeal := J, isPrime := ⋯ }
this : ¬↑s ⊆ ↑↑I
r : S
hrs : r ∈ ↑s
hrI : r ∉ ↑↑I
⊢ ∀ (r_1 : R),
    (↑↑(IsLocalization.map (Localization.AtPrime J) Algebra.TensorProduct.includeRight.toRingHom ⋯)).toFun
        ((algebraMap R (Localization.Away r)) r_1) =
      (algebraMap R (Localization.AtPrime J)) r_1

Tactic:
simp [IsScalarTower.algebraMap_apply R S (Localization.Away r),
        -Algebra.TensorProduct.algebraMap_apply,
        ← IsScalarTower.algebraMap_apply R _ (Localization.AtPrime J)]

Goal state after:
Module: Mathlib.RingTheory.IntegralClosure.Algebra.Ideal

Goal state before:
pp: R : Type u_3
inst✝ : CommRing R
I : Ideal R
P x y : R[X]
hx✝ : x ∈ Algebra.adjoin R {x | ∃ r ∈ I, C r * X = x}
hy✝ : y ∈ Algebra.adjoin R {x | ∃ r ∈ I, C r * X = x}
hx : ∀ (i : ℕ), x.coeff i ∈ I ^ i
hy : ∀ (i : ℕ), y.coeff i ∈ I ^ i
i : ℕ
x✝ : ℕ × ℕ
j₁ j₂ : ℕ
hj : (j₁, j₂) ∈ Finset.antidiagonal i
⊢ j₁ + j₂ = i

Tactic:
by simpa using hj

Goal state after:
Module: Mathlib.RingTheory.Conductor

Goal state before:
pp: case refine_2
R : Type u_1
S : Type u_2
inst✝² : CommRing R
inst✝¹ : CommRing S
inst✝ : Algebra R S
x : S
I : Ideal R
hx : comap (algebraMap R S) (conductor R x) ⊔ I = ⊤
h_alg : Function.Injective ⇑(algebraMap (↥R[x]) S)
f : ↥R[x] ⧸ Ideal.map (algebraMap R ↥R[x]) I →+* S ⧸ Ideal.map (algebraMap R S) I :=
  Ideal.Quotient.lift (Ideal.map (algebraMap R ↥R[x]) I)
    ((Ideal.Quotient.mk (Ideal.map (algebraMap R S) I)).comp (algebraMap (↥R[x]) S)) ⋯
⊢ Function.Surjective ⇑f

Tactic:
refine Ideal.Quotient.lift_surjective_of_surjective _ _ fun y => ?_
    obtain ⟨z, hz⟩ := Ideal.Quotient.mk_surjective y
    have : z ∈ conductor R x ⊔ I.map (algebraMap R S) := by
      suffices conductor R x ⊔ I.map (algebraMap R S) = ⊤ by simp only [this, Submodule.mem_top]
      rw [Ideal.eq_top_iff_one] at hx ⊢
      replace hx := Ideal.mem_map_of_mem (algebraMap R S) hx
      rw [Ideal.map_sup, map_one] at hx
      exact (sup_le_sup
        (show ((conductor R x).comap (algebraMap R S)).map (algebraMap R S) ≤ conductor R x
          from Ideal.map_comap_le)
          (le_refl (I.map (algebraMap R S)))) hx
    rw [← Ideal.mem_quotient_iff_mem_sup, hz, Ideal.mem_map_iff_of_surjective] at this
    · obtain ⟨u, hu, hu'⟩ := this
      use ⟨u, conductor_subset_adjoin hu⟩
      simp only [← hu']
      rfl
    · exact Ideal.Quotient.mk_surjective

Goal state after:
Module: Mathlib.RingTheory.QuasiFinite.Weakly

Goal state before:
pp: S : Type u_2
inst✝⁴ : CommRing S
q : Ideal S
inst✝³ : q.IsPrime
K : Type u_4
inst✝² : Field K
inst✝¹ : Algebra K S
inst✝ : WeaklyQuasiFiniteAt K q
⊢ Module.Finite K (Localization.AtPrime q)

Tactic:
by
  have H : Algebra.WeaklyQuasiFiniteAt K q := ‹_›
  rw [Algebra.weaklyQuasiFiniteAt_iff, ← Ideal.over_def q ⊥, Ideal.map_bot] at H
  have : QuasiFinite K (Localization.AtPrime q) := .of_surjective_algHom
    (AlgEquiv.quotientBot K _).toAlgHom (AlgEquiv.quotientBot K _).surjective
  exact .of_quasiFinite

Goal state after:
Module: Mathlib.AlgebraicGeometry.Sites.SmallAffineZariski

Goal state before:
pp: X : Scheme
U V : X.AffineZariskiSite
s : Set ↑Γ(X, U.toOpens)
f : V ⟶ U
⊢ (Sieve.generate (U.presieveOfSections s)).arrows f ↔ ∃ f ∈ s, ∃ g, X.basicOpen (f * g) = V.toOpens

Tactic:
obtain ⟨V, hV⟩ := V

Goal state after:
X : Scheme
U : X.AffineZariskiSite
s : Set ↑Γ(X, U.toOpens)
V : X.Opens
hV : IsAffineOpen V
f : ⟨V, hV⟩ ⟶ U
⊢ (Sieve.generate (U.presieveOfSections s)).arrows f ↔ ∃ f ∈ s, ∃ g, X.basicOpen (f * g) = toOpens ⟨V, hV⟩
Module: Mathlib.FieldTheory.RatFunc.Basic

Goal state before:
pp: R : Type u_3
S : Type u_4
F : Type u_5
inst✝³ : CommRing R
inst✝² : CommRing S
inst✝¹ : FunLike F R[X] S[X]
inst✝ : MonoidHomClass F R[X] S[X]
φ : F
hφ : R[X]⁰ ≤ Submonoid.comap φ S[X]⁰
hf : Function.Injective ⇑φ
⊢ Function.Injective ⇑(map φ hφ)

Tactic:
by
  rintro ⟨x⟩ ⟨y⟩ h
  induction x using Localization.induction_on
  induction y using Localization.induction_on
  simpa only [map_apply_ofFractionRing_mk, ofFractionRing_injective.eq_iff,
    Localization.mk_eq_mk_iff, Localization.r_iff_exists, mul_cancel_left_coe_nonZeroDivisors,
    exists_const, ← map_mul, hf.eq_iff] using h

Goal state after:
Module: Mathlib.AlgebraicGeometry.Morphisms.QuasiFinite

Goal state before:
pp: X Y : Scheme
f : X ⟶ Y
x : ↥X
hx : QuasiFiniteAt f x
V : X.Opens
hV : IsAffineOpen V
U : Y.Opens
hU : IsAffineOpen U
hVU : V ≤ f ⁻¹ᵁ U
hxV : x ∈ V.carrier
algInst✝¹ : Algebra ↑Γ(Y, U) ↑Γ(X, V) := (CommRingCat.Hom.hom (appLE f U V hVU)).toAlgebra
algInst✝ : Algebra ↑(Y.presheaf.obj (Opposite.op U)) ↑(Y.presheaf.stalk (f x)) :=
  (CommRingCat.Hom.hom (Y.presheaf.germ U (f x) ⋯)).toAlgebra
⊢ (CommRingCat.Hom.hom (Y.presheaf.germ U (f x) ⋯)).QuasiFinite

Tactic:
have := hU.isLocalization_stalk ⟨f x, (hVU hxV)⟩

Goal state after:
X Y : Scheme
f : X ⟶ Y
x : ↥X
hx : QuasiFiniteAt f x
V : X.Opens
hV : IsAffineOpen V
U : Y.Opens
hU : IsAffineOpen U
hVU : V ≤ f ⁻¹ᵁ U
hxV : x ∈ V.carrier
algInst✝¹ : Algebra ↑Γ(Y, U) ↑Γ(X, V) := (CommRingCat.Hom.hom (appLE f U V hVU)).toAlgebra
algInst✝ : Algebra ↑(Y.presheaf.obj (Opposite.op U)) ↑(Y.presheaf.stalk (f x)) :=
  (CommRingCat.Hom.hom (Y.presheaf.germ U (f x) ⋯)).toAlgebra
this : IsLocalization.AtPrime (↑(Y.presheaf.stalk ↑⟨f x, ⋯⟩)) (hU.primeIdealOf ⟨f x, ⋯⟩).asIdeal
⊢ (CommRingCat.Hom.hom (Y.presheaf.germ U (f x) ⋯)).QuasiFinite
Module: Mathlib.FieldTheory.RatFunc.Basic

Goal state before:
pp: K : Type u
inst✝¹ : CommRing K
inst✝ : IsDomain K
P : Sort v
p q : K[X]
f : K[X] → K[X] → P
f0 : ∀ (p : K[X]), f p 0 = f 0 1
H : ∀ {p q a : K[X]}, q ≠ 0 → a ≠ 0 → f (a * p) (a * q) = f p q
⊢ ((algebraMap K[X] K⟮X⟯) p / (algebraMap K[X] K⟮X⟯) q).liftOn' f H = f p q

Tactic:
rw [RatFunc.liftOn', liftOn_div _ _ _ f0]
  apply liftOn_condition_of_liftOn'_condition H

Goal state after:
Module: Mathlib.FieldTheory.RatFunc.Basic

Goal state before:
pp: K : Type u
inst✝ : Field K
x : K⟮X⟯
p q a : K[X]
hq : q ≠ 0
ha : a ≠ 0
⊢ (if a * q = 0 then (0, 1)
    else
      (C (a * q / gcd (a * p) (a * q)).leadingCoeff⁻¹ * (a * p / gcd (a * p) (a * q)),
        C (a * q / gcd (a * p) (a * q)).leadingCoeff⁻¹ * (a * q / gcd (a * p) (a * q)))) =
    if q = 0 then (0, 1)
    else (C (q / gcd p q).leadingCoeff⁻¹ * (p / gcd p q), C (q / gcd p q).leadingCoeff⁻¹ * (q / gcd p q))

Tactic:
if_neg hq,

Goal state after:
K : Type u
inst✝ : Field K
x : K⟮X⟯
p q a : K[X]
hq : q ≠ 0
ha : a ≠ 0
⊢ (if a * q = 0 then (0, 1)
    else
      (C (a * q / gcd (a * p) (a * q)).leadingCoeff⁻¹ * (a * p / gcd (a * p) (a * q)),
        C (a * q / gcd (a * p) (a * q)).leadingCoeff⁻¹ * (a * q / gcd (a * p) (a * q)))) =
    (C (q / gcd p q).leadingCoeff⁻¹ * (p / gcd p q), C (q / gcd p q).leadingCoeff⁻¹ * (q / gcd p q))
Module: Mathlib.RingTheory.Unramified.LocalStructure

Goal state before:
pp: R : Type u_1
S : Type u_3
inst✝⁸ : CommRing R
inst✝⁷ : CommRing S
inst✝⁶ : Algebra R S
P : Ideal R
inst✝⁵ : P.IsPrime
Q : Ideal S
inst✝⁴ : Q.IsPrime
inst✝³ : Q.LiesOver P
inst✝² : IsUnramifiedAt R Q
x : S
p : R[X]
inst✝¹ : Algebra (Localization.AtPrime P) (Localization.AtPrime Q)
inst✝ : Localization.AtPrime.IsLiesOverAlgebra P Q
hp₁ : Ideal.span {Polynomial.map (algebraMap R P.ResidueField) p} = RingHom.ker (aeval (1 ⊗ₜ[R] x)).toRingHom
hp₂ : R[x] = ⊤
Q' : Ideal (P.Fiber S) := ((PrimeSpectrum.primesOverOrderIsoFiber R S P) ⟨Q, ⋯⟩).asIdeal
this✝³ : Q'.LiesOver Q
this✝² : Q'.LiesOver P
this✝¹ : Algebra (Localization.AtPrime Q) (Localization.AtPrime Q') := Localization.AtPrime.algebraOfLiesOver Q Q'
this✝ : Algebra (Localization.AtPrime P) (Localization.AtPrime Q') := Localization.AtPrime.algebraOfLiesOver P Q'
this : IsUnramifiedAt P.ResidueField Q'
⊢ ¬minpoly P.ResidueField ((algebraMap S Q.ResidueField) x) ^ 2 ∣ Polynomial.map (algebraMap R P.ResidueField) p

Tactic:
have : Function.Surjective (aeval (R := P.ResidueField) ((1 : P.ResidueField) ⊗ₜ[R] x)) := by
    rw [← AlgHom.range_eq_top, ← adjoin_singleton_eq_range_aeval]
    simpa using TensorProduct.adjoin_one_tmul_image_eq_top (A := P.ResidueField) _ hp₂

Goal state after:
R : Type u_1
S : Type u_3
inst✝⁸ : CommRing R
inst✝⁷ : CommRing S
inst✝⁶ : Algebra R S
P : Ideal R
inst✝⁵ : P.IsPrime
Q : Ideal S
inst✝⁴ : Q.IsPrime
inst✝³ : Q.LiesOver P
inst✝² : IsUnramifiedAt R Q
x : S
p : R[X]
inst✝¹ : Algebra (Localization.AtPrime P) (Localization.AtPrime Q)
inst✝ : Localization.AtPrime.IsLiesOverAlgebra P Q
hp₁ : Ideal.span {Polynomial.map (algebraMap R P.ResidueField) p} = RingHom.ker (aeval (1 ⊗ₜ[R] x)).toRingHom
hp₂ : R[x] = ⊤
Q' : Ideal (P.Fiber S) := ((PrimeSpectrum.primesOverOrderIsoFiber R S P) ⟨Q, ⋯⟩).asIdeal
this✝⁴ : Q'.LiesOver Q
this✝³ : Q'.LiesOver P
this✝² : Algebra (Localization.AtPrime Q) (Localization.AtPrime Q') := Localization.AtPrime.algebraOfLiesOver Q Q'
this✝¹ : Algebra (Localization.AtPrime P) (Localization.AtPrime Q') := Localization.AtPrime.algebraOfLiesOver P Q'
this✝ : IsUnramifiedAt P.ResidueField Q'
this : Function.Surjective ⇑(aeval (1 ⊗ₜ[R] x))
⊢ ¬minpoly P.ResidueField ((algebraMap S Q.ResidueField) x) ^ 2 ∣ Polynomial.map (algebraMap R P.ResidueField) p
Module: Mathlib.RingTheory.Unramified.LocalStructure

Goal state before:
pp: R : Type u_1
S : Type u_3
inst✝⁵ : CommRing R
inst✝⁴ : CommRing S
inst✝³ : Algebra R S
Q : Ideal S
inst✝² : Q.IsPrime
inst✝¹ : Module.Finite R S
inst✝ : IsUnramifiedAt R Q
this✝ : Algebra (Localization.AtPrime (Ideal.under R Q)) (Localization.AtPrime Q) :=
  Localization.AtPrime.algebraOfLiesOver (Ideal.under R Q) Q
t : S
htQ : t ∉ Q
htQ' : ∀ Q' ∈ (Ideal.under R Q).primesOver S, Q' ≠ Q → t ∈ Q'
ht : (Ideal.under R Q).ResidueField[(algebraMap S Q.ResidueField) t] = ⊤
p : Ideal R := Ideal.under R Q
this : Algebra (Localization.AtPrime p) (Localization.AtPrime (Ideal.under (↥R[t]) Q)) :=
  Localization.AtPrime.algebraOfLiesOver p (Ideal.under (↥R[t]) Q)
⊢ ∃ x,
    (Ideal.under (↥R[x]) Q).primesOver S = {Q} ∧
      Function.Bijective ⇑(algebraMap (Ideal.under (↥R[x]) Q).ResidueField Q.ResidueField)

Tactic:
let := Localization.AtPrime.algebraOfLiesOver (Q.under R[t]) Q

Goal state after:
R : Type u_1
S : Type u_3
inst✝⁵ : CommRing R
inst✝⁴ : CommRing S
inst✝³ : Algebra R S
Q : Ideal S
inst✝² : Q.IsPrime
inst✝¹ : Module.Finite R S
inst✝ : IsUnramifiedAt R Q
this✝¹ : Algebra (Localization.AtPrime (Ideal.under R Q)) (Localization.AtPrime Q) :=
  Localization.AtPrime.algebraOfLiesOver (Ideal.under R Q) Q
t : S
htQ : t ∉ Q
htQ' : ∀ Q' ∈ (Ideal.under R Q).primesOver S, Q' ≠ Q → t ∈ Q'
ht : (Ideal.under R Q).ResidueField[(algebraMap S Q.ResidueField) t] = ⊤
p : Ideal R := Ideal.under R Q
this✝ : Algebra (Localization.AtPrime p) (Localization.AtPrime (Ideal.under (↥R[t]) Q)) :=
  Localization.AtPrime.algebraOfLiesOver p (Ideal.under (↥R[t]) Q)
this : Algebra (Localization.AtPrime (Ideal.under (↥R[t]) Q)) (Localization.AtPrime Q) :=
  Localization.AtPrime.algebraOfLiesOver (Ideal.under (↥R[t]) Q) Q
⊢ ∃ x,
    (Ideal.under (↥R[x]) Q).primesOver S = {Q} ∧
      Function.Bijective ⇑(algebraMap (Ideal.under (↥R[x]) Q).ResidueField Q.ResidueField)
Module: Mathlib.RingTheory.Polynomial.DegreeLT

Goal state before:
pp: case refine_2
m n : ℕ
R : Type u_2
inst✝ : Ring R
f : ↥R[X]_(m + n)
a✝ : Nontrivial R
⊢ ↑((addLinearEquiv R m n) f).1 ∈ R[X]_m

Tactic:
exact Subtype.prop _

Goal state after:
Module: Mathlib.RingTheory.Polynomial.Resultant.Basic

Goal state before:
pp: case pos
R : Type u_1
inst✝ : Semiring R
f : R[X]
hf : 0 < f.natDegree
hn : f.natDegree = 0
⊢ f.sylvesterDeriv.updateRow ⟨2 * f.natDegree - 2, ⋯⟩ (f.leadingCoeff • f.sylvesterDeriv ⟨2 * f.natDegree - 2, ⋯⟩) =
    (derivative f).sylvester f (f.natDegree - 1) f.natDegree

pp: case neg
R : Type u_1
inst✝ : Semiring R
f : R[X]
hf : 0 < f.natDegree
hn : ¬f.natDegree = 0
⊢ f.sylvesterDeriv.updateRow ⟨2 * f.natDegree - 2, ⋯⟩ (f.leadingCoeff • f.sylvesterDeriv ⟨2 * f.natDegree - 2, ⋯⟩) =
    (derivative f).sylvester f (f.natDegree - 1) f.natDegree

Tactic:
· ext ⟨i, hi⟩; lia

Goal state after:
case neg
R : Type u_1
inst✝ : Semiring R
f : R[X]
hf : 0 < f.natDegree
hn : ¬f.natDegree = 0
⊢ f.sylvesterDeriv.updateRow ⟨2 * f.natDegree - 2, ⋯⟩ (f.leadingCoeff • f.sylvesterDeriv ⟨2 * f.natDegree - 2, ⋯⟩) =
    (derivative f).sylvester f (f.natDegree - 1) f.natDegree
Module: Mathlib.RingTheory.Smooth.IntegralClosure

Goal state before:
pp: R : Type u_1
S : Type u_2
B : Type u_3
inst✝⁵ : CommRing R
inst✝⁴ : CommRing S
inst✝³ : Algebra R S
inst✝² : CommRing B
inst✝¹ : Algebra R B
inst✝ : Algebra.IsStandardEtale R S
x : S ⊗[R] B
hx : x ∈ integralClosure S (S ⊗[R] B)
⊢ x ∈ (Algebra.TensorProduct.map (AlgHom.id S S) (integralClosure R B).val).range

Tactic:
refine Algebra.adjoin_le ?_ (mem_adjoin_map_integralClosure_of_isStandardEtale x hx)

Goal state after:
R : Type u_1
S : Type u_2
B : Type u_3
inst✝⁵ : CommRing R
inst✝⁴ : CommRing S
inst✝³ : Algebra R S
inst✝² : CommRing B
inst✝¹ : Algebra R B
inst✝ : Algebra.IsStandardEtale R S
x : S ⊗[R] B
hx : x ∈ integralClosure S (S ⊗[R] B)
⊢ ↑(Subalgebra.map Algebra.TensorProduct.includeRight (integralClosure R B)) ⊆
    ↑(Algebra.TensorProduct.map (AlgHom.id S S) (integralClosure R B).val).range
Module: Mathlib.RingTheory.Polynomial.Resultant.Basic

Goal state before:
pp: n : ℕ
IH :
  ∀ m < n,
    ∀ {K : Type u_3} [inst : Field K] (f g : K[X]),
      f.Monic →
        g.Monic →
          f.Splits →
            g.Splits →
              g.natDegree ≤ f.natDegree →
                f.natDegree + g.natDegree = m →
                  f.resultant g = (Multiset.map (fun ij ↦ ij.1 - ij.2) (f.roots ×ˢ g.roots)).prod
K : Type u_3
inst✝ : Field K
f g : K[X]
hf : f.Monic
hg : g.Monic
hf' : f.Splits
hg' : g.Splits
hfg : g.natDegree ≤ f.natDegree
hN : f.natDegree + g.natDegree = n
hr : ¬g ∣ f
r : K[X] := C (f %ₘ g).leadingCoeff⁻¹ * (f %ₘ g)
hr₀ : f %ₘ g ≠ 0
hrd : r.natDegree < g.natDegree
⊢ ((f %ₘ g).coeff (f %ₘ g).natDegree)⁻¹ * (f %ₘ g).coeff (f %ₘ g).natDegree = 1

Tactic:
inv_mul_cancel₀ (by simpa)

Goal state after:
n : ℕ
IH :
  ∀ m < n,
    ∀ {K : Type u_3} [inst : Field K] (f g : K[X]),
      f.Monic →
        g.Monic →
          f.Splits →
            g.Splits →
              g.natDegree ≤ f.natDegree →
                f.natDegree + g.natDegree = m →
                  f.resultant g = (Multiset.map (fun ij ↦ ij.1 - ij.2) (f.roots ×ˢ g.roots)).prod
K : Type u_3
inst✝ : Field K
f g : K[X]
hf : f.Monic
hg : g.Monic
hf' : f.Splits
hg' : g.Splits
hfg : g.natDegree ≤ f.natDegree
hN : f.natDegree + g.natDegree = n
hr : ¬g ∣ f
r : K[X] := C (f %ₘ g).leadingCoeff⁻¹ * (f %ₘ g)
hr₀ : f %ₘ g ≠ 0
hrd : r.natDegree < g.natDegree
⊢ 1 = 1
Module: Mathlib.RingTheory.Polynomial.Resultant.Basic

Goal state before:
pp: case neg
n : ℕ
IH :
  ∀ m < n,
    ∀ {K : Type u_3} [inst : Field K] (f g : K[X]),
      f.Monic →
        g.Monic →
          f.Splits →
            g.Splits →
              g.natDegree ≤ f.natDegree →
                f.natDegree + g.natDegree = m →
                  f.resultant g = (Multiset.map (fun ij ↦ ij.1 - ij.2) (f.roots ×ˢ g.roots)).prod
K : Type u_3
inst✝ : Field K
f g : K[X]
hf : f.Monic
hg : g.Monic
hf' : f.Splits
hg' : g.Splits
hfg : g.natDegree ≤ f.natDegree
hN : f.natDegree + g.natDegree = n
hr✝ : ¬g ∣ f
r : K[X] := C (f %ₘ g).leadingCoeff⁻¹ * (f %ₘ g)
hr₀ : f %ₘ g ≠ 0
hrd : r.natDegree < g.natDegree
hr : r.Monic
L : Type u_3 := r.SplittingField
⊢ f.resultant g = (Multiset.map (fun ij ↦ ij.1 - ij.2) (f.roots ×ˢ g.roots)).prod

Tactic:
have := IH _ (by simp; lia)
    (g.map (algebraMap K L)) (r.map (algebraMap K L)) (hg.map _) (hr.map _)
    (hg'.map _) (SplittingField.splits _) (by simpa [r, natDegree_C_mul, hr₀] using hrd.le) rfl

Goal state after:
case neg
n : ℕ
IH :
  ∀ m < n,
    ∀ {K : Type u_3} [inst : Field K] (f g : K[X]),
      f.Monic →
        g.Monic →
          f.Splits →
            g.Splits →
              g.natDegree ≤ f.natDegree →
                f.natDegree + g.natDegree = m →
                  f.resultant g = (Multiset.map (fun ij ↦ ij.1 - ij.2) (f.roots ×ˢ g.roots)).prod
K : Type u_3
inst✝ : Field K
f g : K[X]
hf : f.Monic
hg : g.Monic
hf' : f.Splits
hg' : g.Splits
hfg : g.natDegree ≤ f.natDegree
hN : f.natDegree + g.natDegree = n
hr✝ : ¬g ∣ f
r : K[X] := C (f %ₘ g).leadingCoeff⁻¹ * (f %ₘ g)
hr₀ : f %ₘ g ≠ 0
hrd : r.natDegree < g.natDegree
hr : r.Monic
L : Type u_3 := r.SplittingField
this :
  (map (algebraMap K L) g).resultant (map (algebraMap K L) r) =
    (Multiset.map (fun ij ↦ ij.1 - ij.2) ((map (algebraMap K L) g).roots ×ˢ (map (algebraMap K L) r).roots)).prod
⊢ f.resultant g = (Multiset.map (fun ij ↦ ij.1 - ij.2) (f.roots ×ˢ g.roots)).prod
Module: Mathlib.RingTheory.Polynomial.UniversalFactorizationRing

Goal state before:
pp: R : Type u_1
S : Type u_2
T : Type u_3
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : CommRing T
inst✝¹ : Algebra R S
inst✝ : Algebra R T
n m k : ℕ
hn : n = m + k
f : MvPolynomial (Fin n) R →ₐ[R] S
⊢ (fun p ↦ aeval fun x ↦ (↑p).coeff ↑x) ((fun f ↦ (MonicDegreeEq.freeMonic R n).map f.toRingHom) f) = f

Tactic:
ext i; simp [coeff_freeMonic]

Goal state after:
Module: Mathlib.AlgebraicGeometry.Normalization

Goal state before:
pp: X✝ Y✝ : Scheme
f✝ : X✝ ⟶ Y✝
inst✝⁴ : QuasiCompact f✝
inst✝³ : QuasiSeparated f✝
X S Y : Scheme
f : X ⟶ S
g : Y ⟶ S
inst✝² : QuasiCompact f
inst✝¹ : QuasiSeparated f
inst✝ : Smooth g
x : ↥(pullback (fromNormalization f) g)
U : TopologicalSpace.Opens ↥S
hU : U ∈ S.affineOpens
hxU : (pullback.snd (fromNormalization f) g ≫ g) x ∈ ↑U
V : TopologicalSpace.Opens ↥Y
hV : V ∈ Y.affineOpens
hxV : (pullback.snd (fromNormalization f) g) x ∈ ↑V
hVU : V ≤ g ⁻¹ᵁ U
W : (pullback (fromNormalization f) g).Opens := pullback.snd (fromNormalization f) g ⁻¹ᵁ V
⊢ W = pullback.fst (fromNormalization f) g ⁻¹ᵁ fromNormalization f ⁻¹ᵁ U ⊓ pullback.snd (fromNormalization f) g ⁻¹ᵁ V

Tactic:
W,

Goal state after:
X✝ Y✝ : Scheme
f✝ : X✝ ⟶ Y✝
inst✝⁴ : QuasiCompact f✝
inst✝³ : QuasiSeparated f✝
X S Y : Scheme
f : X ⟶ S
g : Y ⟶ S
inst✝² : QuasiCompact f
inst✝¹ : QuasiSeparated f
inst✝ : Smooth g
x : ↥(pullback (fromNormalization f) g)
U : TopologicalSpace.Opens ↥S
hU : U ∈ S.affineOpens
hxU : (pullback.snd (fromNormalization f) g ≫ g) x ∈ ↑U
V : TopologicalSpace.Opens ↥Y
hV : V ∈ Y.affineOpens
hxV : (pullback.snd (fromNormalization f) g) x ∈ ↑V
hVU : V ≤ g ⁻¹ᵁ U
W : (pullback (fromNormalization f) g).Opens := pullback.snd (fromNormalization f) g ⁻¹ᵁ V
⊢ pullback.snd (fromNormalization f) g ⁻¹ᵁ V =
    pullback.fst (fromNormalization f) g ⁻¹ᵁ fromNormalization f ⁻¹ᵁ U ⊓ pullback.snd (fromNormalization f) g ⁻¹ᵁ V
Module: Mathlib.RingTheory.Polynomial.Resultant.Basic

Goal state before:
pp: case injective
R✝ : Type u_1
inst✝² : CommRing R✝
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
φ : R →+* S
hφ : Function.Injective ⇑φ
f : R[X]
IH : (map φ f).resultant (map φ f) = 0 ^ (map φ f).natDegree
⊢ f.resultant f = 0 ^ f.natDegree

Tactic:
| injective R S φ hφ f IH =>

Goal state after:
Module: Mathlib.RingTheory.Polynomial.Resultant.Basic

Goal state before:
pp: R✝ : Type u_1
inst✝¹ : CommRing R✝
R : Type u_1
inst✝ : Field R
f : R[X]
hf' : f.Splits
g : R[X]
r : R
hf : f ≠ 0
hg : g ≠ 0
hf0 : ¬f.natDegree = 0
hg0 : ¬g.natDegree = 0
hr : r ≠ 0
| (f.scaleRoots r).resultant (g.scaleRoots r) (f.scaleRoots r).natDegree g.natDegree

Tactic:
← natDegree_scaleRoots g r

Goal state after:
R✝ : Type u_1
inst✝¹ : CommRing R✝
R : Type u_1
inst✝ : Field R
f : R[X]
hf' : f.Splits
g : R[X]
r : R
hf : f ≠ 0
hg : g ≠ 0
hf0 : ¬f.natDegree = 0
hg0 : ¬g.natDegree = 0
hr : r ≠ 0
| (f.scaleRoots r).resultant (g.scaleRoots r) (f.scaleRoots r).natDegree
Module: Mathlib.RingTheory.Polynomial.Resultant.Basic

Goal state before:
pp: case inr.inr.injective
R✝ : Type u_1
inst✝² : CommRing R✝
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
φ : R →+* S
hφ : Function.Injective ⇑φ
f : R[X]
IH :
  ∀ (g : S[X]) (r : S),
    map φ f ≠ 0 →
      g ≠ 0 →
        ((map φ f).scaleRoots r).resultant (g.scaleRoots r) (map φ f).natDegree g.natDegree =
          r ^ ((map φ f).natDegree * g.natDegree) * (map φ f).resultant g
g : R[X]
r : R
hf : f ≠ 0
hg : g ≠ 0
⊢ (f.scaleRoots r).resultant (g.scaleRoots r) f.natDegree g.natDegree = r ^ (f.natDegree * g.natDegree) * f.resultant g

Tactic:
| injective R S φ hφ f IH =>

Goal state after:
Module: Mathlib.RingTheory.Polynomial.Resultant.Basic

Goal state before:
pp: case injective
R✝ : Type u_1
inst✝² : CommRing R✝
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
φ : R →+* S
hφ : Function.Injective ⇑φ
f : R[X]
IH : ∀ (g : S[X]) (r : S), ((taylor r) (map φ f)).resultant ((taylor r) g) = (map φ f).resultant g
g : R[X]
r : R
⊢ ((taylor r) f).resultant ((taylor r) g) = f.resultant g

Tactic:
| injective R S φ hφ f IH =>

Goal state after:
Module: Mathlib.CategoryTheory.Monoidal.Cartesian.Grp

Goal state before:
pp: C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : CartesianMonoidalCategory C
G : C
inst✝ : GrpObj G
⊢ lift (fst G G) (snd G G) ≫ μ = μ

Tactic:
lift_fst_snd,

Goal state after:
C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : CartesianMonoidalCategory C
G : C
inst✝ : GrpObj G
⊢ 𝟙 (G ⊗ G) ≫ μ = μ