-- Mathlib/Analysis/Convex/GaugeRescale.lean
theorem exists_homeomorph_image_eq {s t : Set E}
    (hsc : Convex ℝ s) (hsne : (interior s).Nonempty) (hsb : IsVonNBounded ℝ s)
    (hst : Convex ℝ t) (htne : (interior t).Nonempty) (htb : IsVonNBounded ℝ t) :
    ∃ e : E ≃ₜ E, e '' interior s = interior t ∧ e '' closure s = closure t ∧
      e '' frontier s = frontier t

Proof state:
case intro.intro
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htb : IsVonNBounded ℝ t
x : E
hx : x ∈ interior s
y : E
hy : y ∈ interior t
h : E ≃ₜ E := gaugeRescaleHomeomorph (-x +ᵥ s) (-y +ᵥ t) ⋯ ⋯ ⋯ ⋯ ⋯ ⋯
⊢ ∃ e, ⇑e '' interior s = interior t ∧ ⇑e '' closure s = closure t

Tactic:
refine ⟨.trans (.addLeft (-x)) <| h.trans <| .addLeft y, ?_, ?_⟩

Result:
case intro.intro.refine_1
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htb : IsVonNBounded ℝ t
x : E
hx : x ∈ interior s
y : E
hy : y ∈ interior t
h : E ≃ₜ E := gaugeRescaleHomeomorph (-x +ᵥ s) (-y +ᵥ t) ⋯ ⋯ ⋯ ⋯ ⋯ ⋯
⊢ ⇑((Homeomorph.addLeft (-x)).trans (h.trans (Homeomorph.addLeft y))) '' interior s = interior t

case intro.intro.refine_2
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htb : IsVonNBounded ℝ t
x : E
hx : x ∈ interior s
y : E
hy : y ∈ interior t
h : E ≃ₜ E := gaugeRescaleHomeomorph (-x +ᵥ s) (-y +ᵥ t) ⋯ ⋯ ⋯ ⋯ ⋯ ⋯
⊢ ⇑((Homeomorph.addLeft (-x)).trans (h.trans (Homeomorph.addLeft y))) '' closure s = closure t

Proof state:
case intro.intro.refine_1
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htb : IsVonNBounded ℝ t
x : E
hx : x ∈ interior s
y : E
hy : y ∈ interior t
h : E ≃ₜ E := gaugeRescaleHomeomorph (-x +ᵥ s) (-y +ᵥ t) ⋯ ⋯ ⋯ ⋯ ⋯ ⋯
⊢ ⇑((Homeomorph.addLeft (-x)).trans (h.trans (Homeomorph.addLeft y))) '' interior s = interior t

Tactic:
calc
  (fun a ↦ y + h (-x + a)) '' interior s = y +ᵥ h '' interior (-x +ᵥ s) := by
    simp_rw [interior_vadd, ← image_vadd, image_image, vadd_eq_add]
  _ = _ := by rw [image_gaugeRescaleHomeomorph_interior, interior_vadd, vadd_neg_vadd]

Result:
no goals

Proof state:
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htb : IsVonNBounded ℝ t
x : E
hx : x ∈ interior s
y : E
hy : y ∈ interior t
h : E ≃ₜ E := gaugeRescaleHomeomorph (-x +ᵥ s) (-y +ᵥ t) ⋯ ⋯ ⋯ ⋯ ⋯ ⋯
⊢ (fun a => y + h (-x + a)) '' closure s = y +ᵥ ⇑h '' closure (-x +ᵥ s)

Tactic:
simp_rw [closure_vadd, ← image_vadd, image_image, vadd_eq_add]

Result:
no goals

Proof state:
case intro.intro
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htb : IsVonNBounded ℝ t
x : E
hx : x ∈ interior s
y : E
hy : y ∈ interior t
⊢ ∃ e, ⇑e '' interior s = interior t ∧ ⇑e '' closure s = closure t

Tactic:
set h : E ≃ₜ E := by
  apply gaugeRescaleHomeomorph (-x +ᵥ s) (-y +ᵥ t) <;>
    simp [← mem_interior_iff_mem_nhds, interior_vadd, mem_vadd_set_iff_neg_vadd_mem, *]

Result:
case intro.intro
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htb : IsVonNBounded ℝ t
x : E
hx : x ∈ interior s
y : E
hy : y ∈ interior t
h : E ≃ₜ E := gaugeRescaleHomeomorph (-x +ᵥ s) (-y +ᵥ t) ⋯ ⋯ ⋯ ⋯ ⋯ ⋯
⊢ ∃ e, ⇑e '' interior s = interior t ∧ ⇑e '' closure s = closure t

Proof state:
case intro
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htne : (interior t).Nonempty
htb : IsVonNBounded ℝ t
x : E
hx : x ∈ interior s
⊢ ∃ e, ⇑e '' interior s = interior t ∧ ⇑e '' closure s = closure t

Tactic:
rcases htne with ⟨y, hy⟩

Result:
case intro.intro
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htb : IsVonNBounded ℝ t
x : E
hx : x ∈ interior s
y : E
hy : y ∈ interior t
⊢ ∃ e, ⇑e '' interior s = interior t ∧ ⇑e '' closure s = closure t

Proof state:
case intro.intro
E : Type u_1
inst✝⁵ : AddCommGroup E
inst✝⁴ : Module ℝ E
inst✝³ : TopologicalSpace E
inst✝² : IsTopologicalAddGroup E
inst✝¹ : ContinuousSMul ℝ E
inst✝ : T1Space E
s t : Set E
hsc : Convex ℝ s
hsne : (interior s).Nonempty
hsb : IsVonNBounded ℝ s
hst : Convex ℝ t
htne : (interior t).Nonempty
htb : IsVonNBounded ℝ t
e : E ≃ₜ E
h₁ : ⇑e '' interior s = interior t
h₂ : ⇑e '' closure s = closure t
⊢ ⇑e '' frontier s = frontier t

Tactic:
simp_rw [← closure_diff_interior, image_diff e.injective, h₁, h₂]

Result:
no goals