Let $M(X,𝒜)$ ($M^{*}(X,𝒜)$) be the $f$-ring of all (bounded) real-measurable functions on a $T$-measurable space $(X,𝒜)$, let $M_K(X,𝒜)$ be the family of all $f\in M(X,𝒜)$ such that $\mathrm{coz}\left(f\right)$ is compact, and let $M_{\infty }(X,𝒜)$ be all $f\in M(X,𝒜)$ that $\{x\in X:|f\left(x\right)|\ge \frac{1}{n}\}$ is compact for any $n\in \mathbb{N}$. We introduce realcompact subrings of $M(X,𝒜)$, we show that $M^{*}(X,𝒜)$ is a realcompact subring of $M(X,𝒜)$, and also $M(X,𝒜)$ is a realcompact if and only if $(X,𝒜)$ is a compact measurable space. For every nonzero real Riesz map $\varphi :M(X,𝒜)\to ℝ$, we prove that there is an element $x_0\in X$ such that $\varphi \left(f\right)=f\left(x_0\right)$ for every $f\in M(X,𝒜)$ if $(X,𝒜)$ is a compact measurable space. We confirm...

Let g be a doubling gauge. We consider the packing measure ${}^g$ and the packing premeasure ${₀}^g$ in a metric space X. We first show that if ${₀}^g\left(X\right)$ is finite, then as a function of X, ${₀}^g$ has a kind of “outer regularity”. Then we prove that if X is complete separable, then $\lambda sup{₀}^g\left(F\right){\le }^g\left(B\right)\le sup{₀}^g\left(F\right)$ for every Borel subset B of X, where the supremum is taken over all compact subsets of B having finite ${₀}^g$-premeasure, and λ is a positive number depending only on the doubling gauge g. As an application, we show that for every doubling gauge...

We present the full descriptive characterizations of the strong McShane integral (or the variational McShane integral) of a Banach space valued function $f:W\to X$ defined on a non-degenerate closed subinterval $W$ of ${ℝ}^m$ in terms of strong absolute continuity or, equivalently, in terms of McShane variational measure $V_{ℳ}F$ generated by the primitive $F:{ℐ}_W\to X$ of $f$, where ${ℐ}_W$ is the family of all closed non-degenerate subintervals of $W$.

We investigate the subadditivity property (also known as the tensorization property) of φ-entropy functionals and their iterations. In particular we show that the only iterated φ-entropies with the tensorization property are iterated variances. This is a complement to the result due to Latała and Oleszkiewicz on characterization of the standard φ-entropies with the tensorization property.

We show that for a wide class of σ-algebras 𝓐, indicatrices of 𝓐-measurable functions admit the same characterization as indicatrices of Lebesgue-measurable functions. In particular, this applies to functions measurable in the sense of Marczewski.

In this paper we establish a formal connection between the average decay of the Fourier transform of functions with respect to a given measure and the Hausdorff behavior of that measure. We also present a generalization of the classical restriction theorem of Stein and Tomas replacing the sphere with sets of prefixed Hausdorff dimension n - 1 + α, with 0 < α < 1.