Theorem: MeasureTheory.toReal_rnDeriv_tilted_left
File: Mathlib/MeasureTheory/Measure/Tilted.lean

tactic: filter_upwards [rnDeriv_tilted_left hfμ hfν] with x hx
state_before: α : Type u_1
mα : MeasurableSpace α
μ : Measure α
f : α → ℝ
ν : Measure α
inst✝¹ : SigmaFinite μ
inst✝ : SigmaFinite ν
hfμ : AEMeasurable f μ
hfν : AEMeasurable f ν
⊢ (fun x => ((μ.tilted f).rnDeriv ν x).toReal) =ᶠ[ae ν] fun x =>
    (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * (μ.rnDeriv ν x).toReal
state_after: case h
α : Type u_1
mα : MeasurableSpace α
μ : Measure α
f : α → ℝ
ν : Measure α
inst✝¹ : SigmaFinite μ
inst✝ : SigmaFinite ν
hfμ : AEMeasurable f μ
hfν : AEMeasurable f ν
x : α
hx : (μ.tilted f).rnDeriv ν x = ENNReal.ofReal (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * μ.rnDeriv ν x
⊢ ((μ.tilted f).rnDeriv ν x).toReal = (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * (μ.rnDeriv ν x).toReal

tactic: rw [hx]
state_before: case h
α : Type u_1
mα : MeasurableSpace α
μ : Measure α
f : α → ℝ
ν : Measure α
inst✝¹ : SigmaFinite μ
inst✝ : SigmaFinite ν
hfμ : AEMeasurable f μ
hfν : AEMeasurable f ν
x : α
hx : (μ.tilted f).rnDeriv ν x = ENNReal.ofReal (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * μ.rnDeriv ν x
⊢ ((μ.tilted f).rnDeriv ν x).toReal = (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * (μ.rnDeriv ν x).toReal
state_after: case h
α : Type u_1
mα : MeasurableSpace α
μ : Measure α
f : α → ℝ
ν : Measure α
inst✝¹ : SigmaFinite μ
inst✝ : SigmaFinite ν
hfμ : AEMeasurable f μ
hfν : AEMeasurable f ν
x : α
hx : (μ.tilted f).rnDeriv ν x = ENNReal.ofReal (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * μ.rnDeriv ν x
⊢ (ENNReal.ofReal (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * μ.rnDeriv ν x).toReal =
    (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * (μ.rnDeriv ν x).toReal

tactic: simp only [ENNReal.toReal_mul, mul_eq_mul_right_iff, ENNReal.toReal_ofReal_eq_iff]
state_before: case h
α : Type u_1
mα : MeasurableSpace α
μ : Measure α
f : α → ℝ
ν : Measure α
inst✝¹ : SigmaFinite μ
inst✝ : SigmaFinite ν
hfμ : AEMeasurable f μ
hfν : AEMeasurable f ν
x : α
hx : (μ.tilted f).rnDeriv ν x = ENNReal.ofReal (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * μ.rnDeriv ν x
⊢ (ENNReal.ofReal (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * μ.rnDeriv ν x).toReal =
    (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * (μ.rnDeriv ν x).toReal
state_after: case h
α : Type u_1
mα : MeasurableSpace α
μ : Measure α
f : α → ℝ
ν : Measure α
inst✝¹ : SigmaFinite μ
inst✝ : SigmaFinite ν
hfμ : AEMeasurable f μ
hfν : AEMeasurable f ν
x : α
hx : (μ.tilted f).rnDeriv ν x = ENNReal.ofReal (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * μ.rnDeriv ν x
⊢ 0 ≤ rexp (f x) / ∫ (x : α), rexp (f x) ∂μ ∨ (μ.rnDeriv ν x).toReal = 0

tactic: exact Or.inl (by positivity)
state_before: case h
α : Type u_1
mα : MeasurableSpace α
μ : Measure α
f : α → ℝ
ν : Measure α
inst✝¹ : SigmaFinite μ
inst✝ : SigmaFinite ν
hfμ : AEMeasurable f μ
hfν : AEMeasurable f ν
x : α
hx : (μ.tilted f).rnDeriv ν x = ENNReal.ofReal (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * μ.rnDeriv ν x
⊢ 0 ≤ rexp (f x) / ∫ (x : α), rexp (f x) ∂μ ∨ (μ.rnDeriv ν x).toReal = 0
state_after: no goals

tactic: positivity
state_before: α : Type u_1
mα : MeasurableSpace α
μ : Measure α
f : α → ℝ
ν : Measure α
inst✝¹ : SigmaFinite μ
inst✝ : SigmaFinite ν
hfμ : AEMeasurable f μ
hfν : AEMeasurable f ν
x : α
hx : (μ.tilted f).rnDeriv ν x = ENNReal.ofReal (rexp (f x) / ∫ (x : α), rexp (f x) ∂μ) * μ.rnDeriv ν x
⊢ 0 ≤ rexp (f x) / ∫ (x : α), rexp (f x) ∂μ
state_after: no goals