∀ {Ω : Type u_1} {m : MeasurableSpace Ω} {ℙ : MeasureTheory.Measure Ω} {X : Ω → ℝ} [MeasureTheory.SFinite ℙ],
  MeasureTheory.HasPDF X ℙ MeasureTheory.volume ↔
    AEMeasurable X ℙ ∧ (MeasureTheory.Measure.map X ℙ).AbsolutelyContinuous MeasureTheory.volume