-- Mathlib/RingTheory/RingHom/Locally.lean
/-- If `P` is preserved by localizations, then so is `Locally P`. -/
lemma locally_localizationPreserves (hPl : LocalizationPreserves P) :
    LocalizationPreserves (Locally P)

Proof state:
case intro.intro.refine_3
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hPl : LocalizationPreserves fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝⁷ : CommRing R
inst✝⁶ : CommRing S
f : R →+* S
M : Submonoid R
R' S' : Type u
inst✝⁵ : CommRing R'
inst✝⁴ : CommRing S'
inst✝³ : Algebra R R'
inst✝² : Algebra S S'
inst✝¹ : IsLocalization M R'
inst✝ : IsLocalization (Submonoid.map f M) S'
s : Set S
hsone : Ideal.span s = ⊤
hs : ∀ t ∈ s, (fun {R S} [CommRing R] [CommRing S] => P) ((algebraMap S (Localization.Away t)).comp f)
Mₐ : (a : ↑s) → Submonoid (Localization.Away ↑a) :=
  fun a => Submonoid.map (algebraMap S (Localization.Away ↑a)) (Submonoid.map f M)
Sₐ : ↑s → Type u := fun a => Localization (Mₐ a)
hM : ∀ (a : ↑s), Submonoid.map ((algebraMap S (Localization.Away ↑a)).comp f) M = Mₐ a
this✝² : ∀ (a : ↑s), IsLocalization (Submonoid.map ((algebraMap S (Localization.Away ↑a)).comp f) M) (Sₐ a)
this✝¹ : ∀ (a : ↑s), IsLocalization (Algebra.algebraMapSubmonoid (Localization.Away ↑a) (Submonoid.map f M)) (Sₐ a)
this✝ : (a : ↑s) → Algebra S' (Sₐ a) :=
  fun a => (IsLocalization.map (Sₐ a) (algebraMap S (Localization.Away ↑a)) ⋯).toAlgebra
this : ∀ (a : ↑s), IsScalarTower S S' (Sₐ a)
a : ↑s
⊢ P ((algebraMap S' (Sₐ a)).comp (IsLocalization.map S' f ⋯))

Tactic:
rw [algebraMap_toAlgebra, IsLocalization.map_comp_map]

Result:
case intro.intro.refine_3
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hPl : LocalizationPreserves fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝⁷ : CommRing R
inst✝⁶ : CommRing S
f : R →+* S
M : Submonoid R
R' S' : Type u
inst✝⁵ : CommRing R'
inst✝⁴ : CommRing S'
inst✝³ : Algebra R R'
inst✝² : Algebra S S'
inst✝¹ : IsLocalization M R'
inst✝ : IsLocalization (Submonoid.map f M) S'
s : Set S
hsone : Ideal.span s = ⊤
hs : ∀ t ∈ s, (fun {R S} [CommRing R] [CommRing S] => P) ((algebraMap S (Localization.Away t)).comp f)
Mₐ : (a : ↑s) → Submonoid (Localization.Away ↑a) :=
  fun a => Submonoid.map (algebraMap S (Localization.Away ↑a)) (Submonoid.map f M)
Sₐ : ↑s → Type u := fun a => Localization (Mₐ a)
hM : ∀ (a : ↑s), Submonoid.map ((algebraMap S (Localization.Away ↑a)).comp f) M = Mₐ a
this✝² : ∀ (a : ↑s), IsLocalization (Submonoid.map ((algebraMap S (Localization.Away ↑a)).comp f) M) (Sₐ a)
this✝¹ : ∀ (a : ↑s), IsLocalization (Algebra.algebraMapSubmonoid (Localization.Away ↑a) (Submonoid.map f M)) (Sₐ a)
this✝ : (a : ↑s) → Algebra S' (Sₐ a) :=
  fun a => (IsLocalization.map (Sₐ a) (algebraMap S (Localization.Away ↑a)) ⋯).toAlgebra
this : ∀ (a : ↑s), IsScalarTower S S' (Sₐ a)
a : ↑s
⊢ P (IsLocalization.map (Sₐ a) ((algebraMap S (Localization.Away ↑a)).comp f) ⋯)

Proof state:
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hPl : LocalizationPreserves fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝⁷ : CommRing R
inst✝⁶ : CommRing S
f : R →+* S
M : Submonoid R
R' S' : Type u
inst✝⁵ : CommRing R'
inst✝⁴ : CommRing S'
inst✝³ : Algebra R R'
inst✝² : Algebra S S'
inst✝¹ : IsLocalization M R'
inst✝ : IsLocalization (Submonoid.map f M) S'
s : Set S
hsone : Ideal.span s = ⊤
hs : ∀ t ∈ s, (fun {R S} [CommRing R] [CommRing S] => P) ((algebraMap S (Localization.Away t)).comp f)
Mₐ : (a : ↑s) → Submonoid (Localization.Away ↑a) :=
  fun a => Submonoid.map (algebraMap S (Localization.Away ↑a)) (Submonoid.map f M)
Sₐ : ↑s → Type u := fun a => Localization (Mₐ a)
hM : ∀ (a : ↑s), Submonoid.map ((algebraMap S (Localization.Away ↑a)).comp f) M = Mₐ a
a : ↑s
⊢ IsLocalization (Submonoid.map ((algebraMap S (Localization.Away ↑a)).comp f) M) (Sₐ a)

Tactic:
rw [hM]

Result:
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hPl : LocalizationPreserves fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝⁷ : CommRing R
inst✝⁶ : CommRing S
f : R →+* S
M : Submonoid R
R' S' : Type u
inst✝⁵ : CommRing R'
inst✝⁴ : CommRing S'
inst✝³ : Algebra R R'
inst✝² : Algebra S S'
inst✝¹ : IsLocalization M R'
inst✝ : IsLocalization (Submonoid.map f M) S'
s : Set S
hsone : Ideal.span s = ⊤
hs : ∀ t ∈ s, (fun {R S} [CommRing R] [CommRing S] => P) ((algebraMap S (Localization.Away t)).comp f)
Mₐ : (a : ↑s) → Submonoid (Localization.Away ↑a) :=
  fun a => Submonoid.map (algebraMap S (Localization.Away ↑a)) (Submonoid.map f M)
Sₐ : ↑s → Type u := fun a => Localization (Mₐ a)
hM : ∀ (a : ↑s), Submonoid.map ((algebraMap S (Localization.Away ↑a)).comp f) M = Mₐ a
a : ↑s
⊢ IsLocalization (Mₐ a) (Sₐ a)