English

Some remarks on points of Lebesgue density and density-degree functions

Functional Analysis 2024-07-18 v1

Abstract

Some properties of mm-density points and density-degree functions are studied. Moreover the following main results are provided: \vskip2mm \begin{itemize} \item {\it Let λ\lambda be a continuous differential form of degree hh in Rn{\mathbf R}^n (with h0h\geq 0) having the following property: There exists a continuous differential form Δ\Delta of degree h+1h+1 in \rnn\rn^n such that \begin{equation*} \int_{{\mathbf R}^n}\Delta\wedge\omega =\int_{{\mathbf R}^n}\lambda\wedge d\omega, \end{equation*} for every CcC^\infty_c differential form ω\omega of degree nh1n-h-1 in Rn{\mathbf R}^n. Moreover let μ\mu be a C1C^1 differential form of degree h+1h+1 in Rn{\mathbf R}^n and set E:={yRnΔ(y)=μ(y)}E:=\{y\in {\mathbf R}^n\,\vert\, \Delta (y)=\mu(y)\}. Then dμ(x)=0d\mu (x) = 0 whenever xx is a (n+1)(n+1)-density point of EE.} \vskip2mm \item {\it Let f:RnRf:{\mathbf R}^n\to\overline {\mathbf R} be a measurable function such that f(x){0}[n,+]f(x)\in \{0\}\cup [n,+\infty] for a.e. xRnx\in {\mathbf R}^n. Then there exists a countable family {Fk}k=1\{F_k\}_{k=1}^\infty of closed subsets of Rn{\mathbf R}^n such that the corresponding sequence of density-degree functions {dFk}k=1\{d_{F_k}\}_{k=1}^\infty converges almost everywhere to ff. }

Cite

@article{arxiv.2407.12343,
  title  = {Some remarks on points of Lebesgue density and density-degree functions},
  author = {Silvano Delladio},
  journal= {arXiv preprint arXiv:2407.12343},
  year   = {2024}
}