Module: Mathlib.RingTheory.Ideal.KrullsHeightTheorem

Goal state before:
pp: case hIN.refine_2
R : Type u_1
inst✝³ : CommRing R
inst✝² : IsNoetherianRing R
inst✝¹ : IsLocalRing R
I : Ideal R
inst✝ : Submodule.IsPrincipal I
hp : IsLocalRing.maximalIdeal R ∈ I.minimalPrimes
q : Ideal R
h₁ : q.IsPrime
h₂ : q < IsLocalRing.maximalIdeal R
this : IsArtinianRing (R ⧸ I)
f : R →+* Localization.AtPrime q := algebraMap R (Localization.AtPrime q)
qs : ℕ →o (Ideal (R ⧸ I))ᵒᵈ := { toFun := fun n ↦ map (Quotient.mk I) (comap f (map f q ^ n)), monotone' := ⋯ }
n : ℕ
hn : comap f (map f q ^ n) ⊔ I = comap f (map f q ^ n.succ) ⊔ I
y : R
hy : y ∈ comap f (map f q ^ n.succ)
z : R
hz : z • Submodule.IsPrincipal.generator I ∈ I
hx : f z ∈ map f q ^ n
⊢ z ∈
    (IsLocalization.orderEmbedding q.primeCompl (Localization.AtPrime q))
      (map (algebraMap R (Localization.AtPrime q)) q ^ n)

pp: case hIN.refine_2.hy
R : Type u_1
inst✝³ : CommRing R
inst✝² : IsNoetherianRing R
inst✝¹ : IsLocalRing R
I : Ideal R
inst✝ : Submodule.IsPrincipal I
hp : IsLocalRing.maximalIdeal R ∈ I.minimalPrimes
q : Ideal R
h₁ : q.IsPrime
h₂ : q < IsLocalRing.maximalIdeal R
this : IsArtinianRing (R ⧸ I)
f : R →+* Localization.AtPrime q := algebraMap R (Localization.AtPrime q)
qs : ℕ →o (Ideal (R ⧸ I))ᵒᵈ := { toFun := fun n ↦ map (Quotient.mk I) (comap f (map f q ^ n)), monotone' := ⋯ }
n : ℕ
hn : comap f (map f q ^ n) ⊔ I = comap f (map f q ^ n.succ) ⊔ I
y : R
hy : y ∈ comap f (map f q ^ n.succ)
z : R
hz : z • Submodule.IsPrincipal.generator I ∈ I
hx : f (Submodule.IsPrincipal.generator I) * f z ∈ map f q ^ n
⊢ IsUnit (f (Submodule.IsPrincipal.generator I))

Tactic:
]

Goal state after:
case hIN.refine_2
R : Type u_1
inst✝³ : CommRing R
inst✝² : IsNoetherianRing R
inst✝¹ : IsLocalRing R
I : Ideal R
inst✝ : Submodule.IsPrincipal I
hp : IsLocalRing.maximalIdeal R ∈ I.minimalPrimes
q : Ideal R
h₁ : q.IsPrime
h₂ : q < IsLocalRing.maximalIdeal R
this : IsArtinianRing (R ⧸ I)
f : R →+* Localization.AtPrime q := algebraMap R (Localization.AtPrime q)
qs : ℕ →o (Ideal (R ⧸ I))ᵒᵈ := { toFun := fun n ↦ map (Quotient.mk I) (comap f (map f q ^ n)), monotone' := ⋯ }
n : ℕ
hn : comap f (map f q ^ n) ⊔ I = comap f (map f q ^ n.succ) ⊔ I
y : R
hy : y ∈ comap f (map f q ^ n.succ)
z : R
hz : z • Submodule.IsPrincipal.generator I ∈ I
hx : f z ∈ map f q ^ n
⊢ z ∈
    (IsLocalization.orderEmbedding q.primeCompl (Localization.AtPrime q))
      (map (algebraMap R (Localization.AtPrime q)) q ^ n)

case hIN.refine_2.hy
R : Type u_1
inst✝³ : CommRing R
inst✝² : IsNoetherianRing R
inst✝¹ : IsLocalRing R
I : Ideal R
inst✝ : Submodule.IsPrincipal I
hp : IsLocalRing.maximalIdeal R ∈ I.minimalPrimes
q : Ideal R
h₁ : q.IsPrime
h₂ : q < IsLocalRing.maximalIdeal R
this : IsArtinianRing (R ⧸ I)
f : R →+* Localization.AtPrime q := algebraMap R (Localization.AtPrime q)
qs : ℕ →o (Ideal (R ⧸ I))ᵒᵈ := { toFun := fun n ↦ map (Quotient.mk I) (comap f (map f q ^ n)), monotone' := ⋯ }
n : ℕ
hn : comap f (map f q ^ n) ⊔ I = comap f (map f q ^ n.succ) ⊔ I
y : R
hy : y ∈ comap f (map f q ^ n.succ)
z : R
hz : z • Submodule.IsPrincipal.generator I ∈ I
hx : f (Submodule.IsPrincipal.generator I) * f z ∈ map f q ^ n
⊢ IsUnit (f (Submodule.IsPrincipal.generator I))