Theorem: Ideal.spanIntNorm_mul
Proof state before:
case neg
R : Type u_1
inst✝¹⁵ : CommRing R
S : Type u_2
inst✝¹⁴ : CommRing S
inst✝¹³ : Algebra R S
inst✝¹² : IsIntegrallyClosed R
inst✝¹¹ : IsDomain R
inst✝¹⁰ : IsDomain S
inst✝⁹ : NoZeroSMulDivisors R S
hRS : Module.Finite R S
inst✝⁸ : IsIntegrallyClosed S
inst✝⁷ : IsSeparable (FractionRing R) (FractionRing S)
inst✝⁶ : IsDomain R
inst✝⁵ : IsDomain S
inst✝⁴ : IsDedekindDomain R
inst✝³ : IsDedekindDomain S
inst✝² : Module.Finite R S
inst✝¹ : Module.Free R S
I J : Ideal S
inst✝ : Nontrivial R
h✝ : Nontrivial S
P : Ideal R
hP : P.IsMaximal
hP0 : ¬P = ⊥
P' : Submonoid S := Algebra.algebraMapSubmonoid S P.primeCompl
Rₚ : Type u_1 := Localization.AtPrime P
Sₚ : Type u_2 := Localization P'
this✝¹⁰ : Algebra Rₚ Sₚ := localizationAlgebra P.primeCompl S
this✝⁹ : IsScalarTower R Rₚ Sₚ
h : P' ≤ S⁰
this✝⁸ : IsDomain Sₚ
this✝⁷ : IsDedekindDomain Sₚ
this✝⁶ : IsPrincipalIdealRing Sₚ
this✝⁵ : IsIntegrallyClosed Rₚ
this✝⁴ : NoZeroSMulDivisors Rₚ Sₚ
this✝³ : Module.Finite Rₚ Sₚ
L : Type u_2 := FractionRing S
g : Sₚ →+* L := IsLocalization.map L (RingHom.id S) h
this✝² : Algebra Sₚ L := g.toAlgebra
this✝¹ : IsScalarTower S Sₚ (FractionRing S)
this✝ : IsFractionRing Sₚ (FractionRing S) :=
  IsFractionRing.isFractionRing_of_isDomain_of_isLocalization P' Sₚ (FractionRing S)
this : IsSeparable (FractionRing Rₚ) (FractionRing Sₚ)
⊢ map (algebraMap R (Localization.AtPrime P)) (spanIntNorm R (I * J)) =
    map (algebraMap R (Localization.AtPrime P)) (spanIntNorm R I * spanIntNorm R J)
Tactic:
simp only [Ideal.map_mul, ← spanIntNorm_localization (R := R) (S := S)
  (Rₘ := Localization.AtPrime P) (Sₘ := Localization P') _ _ P.primeCompl_le_nonZeroDivisors]
Proof state after:
case neg
R : Type u_1
inst✝¹⁵ : CommRing R
S : Type u_2
inst✝¹⁴ : CommRing S
inst✝¹³ : Algebra R S
inst✝¹² : IsIntegrallyClosed R
inst✝¹¹ : IsDomain R
inst✝¹⁰ : IsDomain S
inst✝⁹ : NoZeroSMulDivisors R S
hRS : Module.Finite R S
inst✝⁸ : IsIntegrallyClosed S
inst✝⁷ : IsSeparable (FractionRing R) (FractionRing S)
inst✝⁶ : IsDomain R
inst✝⁵ : IsDomain S
inst✝⁴ : IsDedekindDomain R
inst✝³ : IsDedekindDomain S
inst✝² : Module.Finite R S
inst✝¹ : Module.Free R S
I J : Ideal S
inst✝ : Nontrivial R
h✝ : Nontrivial S
P : Ideal R
hP : P.IsMaximal
hP0 : ¬P = ⊥
P' : Submonoid S := Algebra.algebraMapSubmonoid S P.primeCompl
Rₚ : Type u_1 := Localization.AtPrime P
Sₚ : Type u_2 := Localization P'
this✝¹⁰ : Algebra Rₚ Sₚ := localizationAlgebra P.primeCompl S
this✝⁹ : IsScalarTower R Rₚ Sₚ
h : P' ≤ S⁰
this✝⁸ : IsDomain Sₚ
this✝⁷ : IsDedekindDomain Sₚ
this✝⁶ : IsPrincipalIdealRing Sₚ
this✝⁵ : IsIntegrallyClosed Rₚ
this✝⁴ : NoZeroSMulDivisors Rₚ Sₚ
this✝³ : Module.Finite Rₚ Sₚ
L : Type u_2 := FractionRing S
g : Sₚ →+* L := IsLocalization.map L (RingHom.id S) h
this✝² : Algebra Sₚ L := g.toAlgebra
this✝¹ : IsScalarTower S Sₚ (FractionRing S)
this✝ : IsFractionRing Sₚ (FractionRing S) :=
  IsFractionRing.isFractionRing_of_isDomain_of_isLocalization P' Sₚ (FractionRing S)
this : IsSeparable (FractionRing Rₚ) (FractionRing Sₚ)
⊢ spanIntNorm (Localization.AtPrime P)
      (map (algebraMap S (Localization P')) I * map (algebraMap S (Localization P')) J) =
    spanIntNorm (Localization.AtPrime P) (map (algebraMap S (Localization P')) I) *
      spanIntNorm (Localization.AtPrime P) (map (algebraMap S (Localization P')) J)