English
The singular part respects scalar multiplication by NNReal: (r μ).singularPart ν = r μ.singularPart ν.
Русский
Сингулярная часть сохраняет масштабирование NNReal: (r μ).singularPart ν = r μ.singularPart ν.
LaTeX
$$$ (r\\in\\mathbb{R}_{+}):\\; (r\\cdot μ).singularPart ν = r\\cdot (μ.singularPart ν) $$$
Lean4
theorem eq_rnDeriv₀ [SigmaFinite ν] {s : Measure α} {f : α → ℝ≥0∞} (hf : AEMeasurable f ν) (hs : s ⟂ₘ ν)
(hadd : μ = s + ν.withDensity f) : f =ᵐ[ν] μ.rnDeriv ν :=
(withDensity_eq_iff_of_sigmaFinite hf (measurable_rnDeriv _ _).aemeasurable).mp (eq_withDensity_rnDeriv₀ hf hs hadd)