-- Mathlib/MeasureTheory/VectorMeasure/Basic.lean
theorem map [MeasureSpace β] (h : v ≪ᵥ w) (f : α → β) : v.map f ≪ᵥ w.map f

Proof state:
case neg
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : ¬Measurable f
s : Set β
a✝ : ↑(w.map f) s = 0
⊢ ↑(v.map f) s = 0

Tactic:
rw [map_not_measurable v hf, zero_apply]

Result:
no goals

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
⊢ v.map f ≪ᵥ w.map f

Tactic:
by_cases hf : Measurable f

Result:
case pos
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : Measurable f
⊢ v.map f ≪ᵥ w.map f

case neg
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : ¬Measurable f
⊢ v.map f ≪ᵥ w.map f

Proof state:
case neg
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : ¬Measurable f
⊢ v.map f ≪ᵥ w.map f

Tactic:
intro s _

Result:
case neg
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : ¬Measurable f
s : Set β
a✝ : ↑(w.map f) s = 0
⊢ ↑(v.map f) s = 0

Proof state:
case pos
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : Measurable f
s : Set β
hs : MeasurableSet s
hws : ↑(w.map f) s = 0
⊢ ↑(v.map f) s = 0

Tactic:
rw [map_apply _ hf hs] at hws ⊢

Result:
case pos
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : Measurable f
s : Set β
hs : MeasurableSet s
hws : ↑w (f ⁻¹' s) = 0
⊢ ↑v (f ⁻¹' s) = 0

Proof state:
case pos
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : Measurable f
⊢ v.map f ≪ᵥ w.map f

Tactic:
refine mk fun s hs hws => ?_

Result:
case pos
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : Measurable f
s : Set β
hs : MeasurableSet s
hws : ↑(w.map f) s = 0
⊢ ↑(v.map f) s = 0

Proof state:
case pos
α : Type u_1
β : Type u_2
m : MeasurableSpace α
M : Type u_4
N : Type u_5
inst✝⁴ : AddCommMonoid M
inst✝³ : TopologicalSpace M
inst✝² : AddCommMonoid N
inst✝¹ : TopologicalSpace N
v : VectorMeasure α M
w : VectorMeasure α N
inst✝ : MeasureSpace β
h : v ≪ᵥ w
f : α → β
hf : Measurable f
s : Set β
hs : MeasurableSet s
hws : ↑w (f ⁻¹' s) = 0
⊢ ↑v (f ⁻¹' s) = 0

Tactic:
exact h hws

Result:
no goals