-- Mathlib/RingTheory/RingHom/Locally.lean
/-- `Locally P` is local on the target. -/
lemma locally_ofLocalizationSpanTarget (hP : RespectsIso P) :
    OfLocalizationSpanTarget (Locally P)

Proof state:
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
t : (r : ↑s) → Set (Localization.Away ↑r)
htone : ∀ (r : ↑s), Ideal.span (t r) = ⊤
ht :
  ∀ (r : ↑s),
    ∀ t_1 ∈ t r,
      (fun {R S} [CommRing R] [CommRing S] => P)
        ((algebraMap (Localization.Away ↑r) (Localization.Away t_1)).comp
          ((algebraMap S (Localization.Away ↑r)).comp f))
⊢ Locally (fun {R S} [CommRing R] [CommRing S] => P) f

Tactic:
rw [locally_iff_exists hP]

Result:
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
t : (r : ↑s) → Set (Localization.Away ↑r)
htone : ∀ (r : ↑s), Ideal.span (t r) = ⊤
ht :
  ∀ (r : ↑s),
    ∀ t_1 ∈ t r,
      (fun {R S} [CommRing R] [CommRing S] => P)
        ((algebraMap (Localization.Away ↑r) (Localization.Away t_1)).comp
          ((algebraMap S (Localization.Away ↑r)).comp f))
⊢ ∃ ι s,
    ∃ (_ : Ideal.span (Set.range s) = ⊤),
      ∃ Sₜ x x_1, ∃ (_ : ∀ (i : ι), IsLocalization.Away (s i) (Sₜ i)), ∀ (i : ι), P ((algebraMap S (Sₜ i)).comp f)

Proof state:
case h.hu
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
t : (r : ↑s) → Set (Localization.Away ↑r)
htone : ∀ (r : ↑s), Ideal.span (t r) = ⊤
ht :
  ∀ (r : ↑s),
    ∀ t_1 ∈ t r,
      (fun {R S} [CommRing R] [CommRing S] => P)
        ((algebraMap (Localization.Away ↑r) (Localization.Away t_1)).comp
          ((algebraMap S (Localization.Away ↑r)).comp f))
x✝ : (a : ↑s) × ↑(t a)
a : ↑s
b : ↑(t a)
⊢ IsUnit ((algebraMap S (Localization.Away ↑a)) (↑a ^ (IsLocalization.Away.sec ↑a ↑b).2))

Tactic:
rw [map_pow _ _]

Result:
case h.hu
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
t : (r : ↑s) → Set (Localization.Away ↑r)
htone : ∀ (r : ↑s), Ideal.span (t r) = ⊤
ht :
  ∀ (r : ↑s),
    ∀ t_1 ∈ t r,
      (fun {R S} [CommRing R] [CommRing S] => P)
        ((algebraMap (Localization.Away ↑r) (Localization.Away t_1)).comp
          ((algebraMap S (Localization.Away ↑r)).comp f))
x✝ : (a : ↑s) × ↑(t a)
a : ↑s
b : ↑(t a)
⊢ IsUnit ((algebraMap S (Localization.Away ↑a)) ↑a ^ (IsLocalization.Away.sec ↑a ↑b).2)

Proof state:
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
hs :
  ∀ (r : ↑s),
    (fun {R S} [CommRing R] [CommRing S] => Locally fun {R S} [CommRing R] [CommRing S] => P)
      ((algebraMap S (Localization.Away ↑r)).comp f)
⊢ Locally (fun {R S} [CommRing R] [CommRing S] => P) f

Tactic:
choose t htone ht using hs

Result:
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
t : (r : ↑s) → Set (Localization.Away ↑r)
htone : ∀ (r : ↑s), Ideal.span (t r) = ⊤
ht :
  ∀ (r : ↑s),
    ∀ t_1 ∈ t r,
      (fun {R S} [CommRing R] [CommRing S] => P)
        ((algebraMap (Localization.Away ↑r) (Localization.Away t_1)).comp
          ((algebraMap S (Localization.Away ↑r)).comp f))
⊢ Locally (fun {R S} [CommRing R] [CommRing S] => P) f

Proof state:
case h.hu
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
t : (r : ↑s) → Set (Localization.Away ↑r)
htone : ∀ (r : ↑s), Ideal.span (t r) = ⊤
ht :
  ∀ (r : ↑s),
    ∀ t_1 ∈ t r,
      (fun {R S} [CommRing R] [CommRing S] => P)
        ((algebraMap (Localization.Away ↑r) (Localization.Away t_1)).comp
          ((algebraMap S (Localization.Away ↑r)).comp f))
x✝ : (a : ↑s) × ↑(t a)
a : ↑s
b : ↑(t a)
⊢ IsUnit ((algebraMap S (Localization.Away ↑a)) ↑a ^ (IsLocalization.Away.sec ↑a ↑b).2)

Tactic:
exact IsUnit.pow _ (IsLocalization.Away.algebraMap_isUnit _)

Result:
no goals

Proof state:
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
⊢ OfLocalizationSpanTarget fun {R S} [CommRing R] [CommRing S] => Locally fun {R S} [CommRing R] [CommRing S] => P

Tactic:
intro R S _ _ f s hsone hs

Result:
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
hs :
  ∀ (r : ↑s),
    (fun {R S} [CommRing R] [CommRing S] => Locally fun {R S} [CommRing R] [CommRing S] => P)
      ((algebraMap S (Localization.Away ↑r)).comp f)
⊢ Locally (fun {R S} [CommRing R] [CommRing S] => P) f

Proof state:
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
t : (r : ↑s) → Set (Localization.Away ↑r)
htone : ∀ (r : ↑s), Ideal.span (t r) = ⊤
ht :
  ∀ (r : ↑s),
    ∀ t_1 ∈ t r,
      (fun {R S} [CommRing R] [CommRing S] => P)
        ((algebraMap (Localization.Away ↑r) (Localization.Away t_1)).comp
          ((algebraMap S (Localization.Away ↑r)).comp f))
x✝ : (a : ↑s) × ↑(t a)
a : ↑s
b : ↑(t a)
⊢ IsLocalization.Away ((algebraMap S (Localization.Away ↑a)) (IsLocalization.Away.sec ↑a ↑b).1) (Localization.Away ↑b)

Tactic:
apply IsLocalization.Away.of_associated (r := b.val)

Result:
case h
P : {R S : Type u} → [inst : CommRing R] → [inst_1 : CommRing S] → (R →+* S) → Prop
hP : RespectsIso fun {R S} [CommRing R] [CommRing S] => P
R S : Type u
inst✝¹ : CommRing R
inst✝ : CommRing S
f : R →+* S
s : Set S
hsone : Ideal.span s = ⊤
t : (r : ↑s) → Set (Localization.Away ↑r)
htone : ∀ (r : ↑s), Ideal.span (t r) = ⊤
ht :
  ∀ (r : ↑s),
    ∀ t_1 ∈ t r,
      (fun {R S} [CommRing R] [CommRing S] => P)
        ((algebraMap (Localization.Away ↑r) (Localization.Away t_1)).comp
          ((algebraMap S (Localization.Away ↑r)).comp f))
x✝ : (a : ↑s) × ↑(t a)
a : ↑s
b : ↑(t a)
⊢ Associated (↑b) ((algebraMap S (Localization.Away ↑a)) (IsLocalization.Away.sec ↑a ↑b).1)