-- Mathlib/RingTheory/RingHom/FinitePresentation.lean
theorem finitePresentation_ofLocalizationSpanTarget :
    OfLocalizationSpanTarget @FinitePresentation

Proof state:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
H : ∀ (r : { x // x ∈ s }), ((algebraMap S (Localization.Away ↑r)).comp f).FinitePresentation
this : Algebra R S := f.toAlgebra
⊢ f.FinitePresentation

Tactic:
replace H : ∀ r : s, Algebra.FinitePresentation R (Localization.Away (r : S)) := by
  intro r; simp_rw [RingHom.FinitePresentation] at H
  convert H r; ext; simp_rw [Algebra.smul_def]; rfl

Result:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
⊢ f.FinitePresentation

Proof state:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
hfintype : Algebra.FiniteType R S
⊢ Algebra.FinitePresentation R S

Tactic:
obtain ⟨n, f, hf⟩ := Algebra.FiniteType.iff_quotient_mvPolynomial''.mp hfintype

Result:
case intro.intro
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f✝ : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f✝.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
hfintype : Algebra.FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
⊢ Algebra.FinitePresentation R S

Proof state:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f✝ : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f✝.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
hfintype : Algebra.FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
l : ↑↑s →₀ S
hl : (Finsupp.linearCombination S Subtype.val) l = 1
g' : { x // x ∈ s } → MvPolynomial (Fin n) R
hg' : ∀ (g : { x // x ∈ s }), f (g' g) = ↑g
h' : { x // x ∈ s } → MvPolynomial (Fin n) R
hh' : ∀ (g : { x // x ∈ s }), f (h' g) = l g
I : Ideal (MvPolynomial (Fin n) R) := Ideal.span {∑ g : { x // x ∈ s }, g' g * h' g - 1}
A : Type u_1 := MvPolynomial (Fin n) R ⧸ I
p : MvPolynomial (Fin n) R
hp : p ∈ I
⊢ f p = 0

Tactic:
simp only [Finset.univ_eq_attach, I, Ideal.mem_span_singleton] at hp

Result:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f✝ : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f✝.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
hfintype : Algebra.FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
l : ↑↑s →₀ S
hl : (Finsupp.linearCombination S Subtype.val) l = 1
g' : { x // x ∈ s } → MvPolynomial (Fin n) R
hg' : ∀ (g : { x // x ∈ s }), f (g' g) = ↑g
h' : { x // x ∈ s } → MvPolynomial (Fin n) R
hh' : ∀ (g : { x // x ∈ s }), f (h' g) = l g
I : Ideal (MvPolynomial (Fin n) R) := Ideal.span {∑ g : { x // x ∈ s }, g' g * h' g - 1}
A : Type u_1 := MvPolynomial (Fin n) R ⧸ I
p : MvPolynomial (Fin n) R
hp : ∑ g ∈ s.attach, g' g * h' g - 1 ∣ p
⊢ f p = 0

Proof state:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f✝ : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f✝.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
hfintype : Algebra.FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
⊢ 1 ∈ Ideal.span ↑s

Tactic:
rw [hs]

Result:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f✝ : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f✝.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
hfintype : Algebra.FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
⊢ 1 ∈ ⊤

Proof state:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
hfintype : Algebra.FiniteType R S
⊢ f.FinitePresentation

Tactic:
rw [RingHom.FinitePresentation]

Result:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
hfintype : Algebra.FiniteType R S
⊢ Algebra.FinitePresentation R S

Proof state:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
r : ↑↑s
⊢ Algebra.FiniteType R (Localization.Away ↑r)

Tactic:
infer_instance

Result:
no goals

Proof state:
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f✝ : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
this : Algebra R S := f✝.toAlgebra
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
hfintype : Algebra.FiniteType R S
n : ℕ
f : MvPolynomial (Fin n) R →ₐ[R] S
hf : Function.Surjective ⇑f
⊢ 1 ∈ ⊤

Tactic:
trivial

Result:
no goals

Proof state:
case h.e'_5.h.h
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
this : Algebra R S := f.toAlgebra
r : { x // x ∈ s }
e_4✝ : OreLocalization.instSemiring = CommSemiring.toSemiring
r✝ : R
x✝ : OreLocalization (Submonoid.powers ↑r) S
⊢ (let_fun I := OreLocalization.instAlgebra;
    r✝ • x✝) =
    r✝ • x✝

Tactic:
simp_rw [Algebra.smul_def]

Result:
case h.e'_5.h.h
R S : Type u_1
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Finset S
hs : Ideal.span ↑s = ⊤
H : ∀ (r : { x // x ∈ s }), Algebra.FinitePresentation R (Localization.Away ↑r)
this : Algebra R S := f.toAlgebra
r : { x // x ∈ s }
e_4✝ : OreLocalization.instSemiring = CommSemiring.toSemiring
r✝ : R
x✝ : OreLocalization (Submonoid.powers ↑r) S
⊢ (algebraMap R (OreLocalization (Submonoid.powers ↑r) S)) r✝ * x✝ =
    (algebraMap R (OreLocalization (Submonoid.powers ↑r) S)) r✝ * x✝