A topological space Y is said to have (AEEP) if the following condition is satisfied: Whenever (X,) is a measurable space and f,g: X → Y are two measurable functions, then the set Δ(f,g) = x ∈ X: f(x) = g(x) is a member of . It is shown that a metrizable space Y has (AEEP) iff the cardinality of Y is not greater than $2^{\aleph ₀}$.

Suppose that $(X,𝒜)$ is a measurable space and $Y$ is a metrizable, Souslin space. Let ${𝒜}^u$ denote the universal completion of $𝒜$. For $x\in X$, let $\underline{f}(x,·)$ be the lower semicontinuous hull of $f(x,·)$. If $f:X\times Y\to \overline{ℝ}$ is $({𝒜}^u\otimes ℬ\left(Y\right),ℬ\left(\overline{ℝ}\right))$-measurable, then $\underline{f}$ is $({𝒜}^u\otimes ℬ\left(Y\right),ℬ\left(\overline{ℝ}\right))$-measurable.

Let $G$ be a locally compact group. Let $L_t$ be the left translation in $L^{\infty }\left(G\right)$, given by $L_{t}f\left(x\right)=f\left(tx\right)$. We characterize (undre a mild set-theoretical hypothesis) the functions $f\in L^{\infty }\left(G\right)$ such that the map $t\to L_{t}f$ from $G$ into $L^{\infty }\left(G\right)$ is scalarly measurable (i.e. for $\phi \in L^{\infty }(G{)}^{*}$, $t\to \phi \left(L_{t}f\right)$ is measurable). We show that it is the case when $t\to \theta \left(L_{f}t\right)$ is measurable for each character $\theta$, and if $G$ is compact, if and only if $f$ is Riemann-measurable. We show that $t\to L_{t}f$ is Borel measurable if and only if $f$ is left uniformly continuous. Some of the measure-theoretic...

We show that the existence of measurable envelopes of all subsets of ℝⁿ with respect to the d-dimensional Hausdorff measure (0 < d < n) is independent of ZFC. We also investigate the consistency of the existence of ${\mathscr{H}}^d$-measurable Sierpiński sets.

We consider a multifunction $F:T\times X\to 2^E$, where T, X and E are separable metric spaces, with E complete. Assuming that F is jointly measurable in the product and a.e. lower semicontinuous in the second variable, we establish the existence of a selection for F which is measurable with respect to the first variable and a.e. continuous with respect to the second one. Our result is in the spirit of [11], where multifunctions of only one variable are considered.

Let $Q={\left(Q_k\right)}_{k\ge 0},Q_0=1,Q_{k+1}=q_k{Q}_k,q_k\ge 2$, be a Cantor scale, ${𝐙}_Q$ the compact projective limit group of the groups $𝐙/Q_k𝐙$, identified to ${\prod }_{0\le j\le k-1}𝐙/q_j𝐙$, and let $\mu$ be its normalized Haar measure. To an element $x=\{a_0,a_1,a_2,\cdots \},0\le a_k\le q_{k+1}-1$, of ${𝐙}_Q$ we associate the sequence of integral valued random variables $x_k={\sum }_{0\le j\le k}{a}_j{Q}_j$. The main result of this article is that, given a complex $𝐐$-multiplicative function $g$ of modulus $1$, we have $$\underset{x_k\to x}{lim}(\frac{1}{x_k}\sum _{n\le x_k-1}g\left(n\right)-\prod _{0\le j\le k}\frac{1}{q_j}\sum _{0\le a\le q_j}g\left(a{Q}_j\right))=0\mu \text{-a.e}.$$

It is proved that if a Frechet space $E$ has $R-N$ property, then $L_p(E,\nu )$ also has $R-N$ property, for $1\&lt;p\&lt;\infty$.

Bessaga and Pełczyński showed that if $c_0$ embeds in the dual $X^{*}$ of a Banach space X, then ${\ell }^1$ embeds as a complemented subspace of X. Pełczyński proved that every infinite-dimensional closed linear subspace of ${\ell }^1$ contains a copy of ${\ell }^1$ that is complemented in ${\ell }^1$. Later, Kadec and Pełczyński proved that every non-reflexive closed linear subspace of $L^1[0,1]$ contains a copy of ${\ell }^1$ that is complemented in $L^1[0,1]$. In this note a traditional sliding hump argument is used to establish a simple mapping property of...

Let $P(\lambda ,D)={\sum }_{\left|\alpha \right|\le m}{a}_{\alpha }\left(\lambda \right)D^{\alpha }$ be a differential operator with constant coefficients $a_{\alpha }$ depending analytically on a parameter $\lambda$. Assume that the family $\{$ P($\lambda$,D)$\}$ is of constant strength. We investigate the equation $P(\lambda ,D){𝔣}_{\lambda }\equiv g_{\lambda }$ where ${𝔤}_{\lambda }$ is a given analytic function of $\lambda$ with values in some space of distributions and the solution ${𝔣}_{\lambda }$ is required to depend analytically on $\lambda$, too. As a special case we obtain a regular fundamental solution of P($\lambda$,D) which depends analytically on $\lambda$. This result answers a question of L. Hörmander. ...