We discuss k-rotundity, weak k-rotundity, C-k-rotundity, weak C-k-rotundity, k-nearly uniform convexity, k-β property, C-I property, C-II property, C-III property and nearly uniform convexity both pointwise and global in Orlicz function spaces equipped with Luxemburg norm. Applications to continuity for the metric projection at a given point are given in Orlicz function spaces with Luxemburg norm.

We produce several situations where some natural subspaces of classical Banach spaces of functions over a compact abelian group contain the space c₀.

Several equivalent conditions are given for the existence of real-valued Baire functions of all classes on a type of $\mathbf{K}$-analytic spaces, called disjoint analytic spaces, and on all pseudocompact spaces. The sequential stability index for the Banach space of bounded continuous real-valued functions on these spaces is shown to be either $0,1$, or $\Omega$ (the first uncountable ordinal). In contrast, the space of bounded real-valued Baire functions of class 1 is shown to contain closed linear subspaces with index...

The classical level function construction of Halperin and Lorentz is extended to Lebesgue spaces with general measures. The construction is also carried farther. In particular, the level function is considered as a monotone map on its natural domain, a superspace of $L^p$. These domains are shown to be Banach spaces which, although closely tied to $L^p$ spaces, are not reflexive. A related construction is given which characterizes their dual spaces.

For a metrizable space X and a finite measure space (Ω, $𝔐$, µ), the space M µ(X) of all equivalence classes (under the relation of equality almost everywhere mod µ) of $𝔐$-measurable functions from Ω to X, whose images are separable, equipped with the topology of convergence in measure, and some of its subspaces are studied. In particular, it is shown that M µ(X) is homeomorphic to a Hilbert space provided µ is (nonzero) nonatomic and X is completely metrizable and has more than one point.

The aim of this paper is to investigate stability of unit ball in Orlicz spaces, endowed with the Luxemburg norm, from the “local” point of view. Firstly, those points of the unit ball are characterized which are stable, i.e., at which the map $z\to \{(x,y):\frac{1}{2}(x+y)=z\}$ is lower-semicontinuous. Then the main theorem is established: An Orlicz space $L^{\varphi }\left(\mu \right)$ has stable unit ball if and only if either $L^{\varphi }\left(\mu \right)$ is finite dimensional or it is isometric to $L^{\infty }\left(\mu \right)$ or $\varphi$ satisfies the condition ${\Delta }_r$ or ${\Delta }_r^0$ (appropriate to the measure $\mu$ and the function...

If G is the closure of $L_{\infty }$ in exp L₂, it is proved that the inclusion between rearrangement invariant spaces E ⊂ F is strictly singular if and only if it is disjointly strictly singular and E ⊊ G. For any Marcinkiewicz space M(φ) ⊂ G such that M(φ) is not an interpolation space between $L_{\infty }$ and G it is proved that there exists another Marcinkiewicz space M(ψ) ⊊ M(φ) with the property that the M(ψ) and M(φ) norms are equivalent on the Rademacher subspace. Applications are given and a question of Milman...

Let $(X,\parallel ·{\parallel }_X)$ be a real Banach space and let $E$ be an ideal of $L^0$ over a $\sigma$-finite measure space $(Ø,\Sigma ,\mu )$. Let $\left(X\right)$ be the space of all strongly $\Sigma$-measurable functions $fØ\to X$ such that the scalar function $\tilde{f}$, defined by $\tilde{f}\left(ø\right)={\parallel f\left(ø\right)\parallel }_X$ for $ø\in Ø$, belongs to $E$. The paper deals with strong topologies on $E\left(X\right)$. In particular, the strong topology $\beta (E\left(X\right),E{\left(X\right)}_n^{\sim })$ ($E{\left(X\right)}_n^{\sim }=$ the order continuous dual of $E\left(X\right)$) is examined. We generalize earlier results of [PC] and [FPS] concerning the strong topologies.

Geometric structure of Cesàro function spaces $Ce{s}_p\left(I\right)$, where I = [0,1] and [0,∞), is investigated. Among other matters we present a description of their dual spaces, characterize the sets of all q ∈ [1,∞] such that $Ce{s}_p[0,1]$ contains isomorphic and complemented copies of $l_q$-spaces, show that Cesàro function spaces fail the fixed point property, give a description of subspaces generated by Rademacher functions in spaces $Ce{s}_p[0,1]$.

The structure of the closed linear span of the Rademacher functions in the Cesàro space $Ce{s}_{\infty }$ is investigated. It is shown that every infinite-dimensional subspace of either is isomorphic to l₂ and uncomplemented in $Ce{s}_{\infty }$, or contains a subspace isomorphic to c₀ and complemented in . The situation is rather different in the p-convexification of $Ce{s}_{\infty }$ if 1 < p < ∞.