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Let E be a Banach space with a supremum type norm induced by a collection of functionals ℒ ⊂ X* where X is a reflexive Banach space. Familiar spaces of this type are BMO, BV, C 0,α(0α≤1), Lq,∾, for q1. For most of these spaces E, the predual E* exists and can be defined by atomic decomposition of its elements. Another typical result, when it is possible to define a rich vanishing subspace E0 ⊂ E is the "two star theorem", namely (E0)*=E*. This fails for E=BV and E=C0,1=Lip.

We prove that the outer $L^p_\mu(\ell^r)$ spaces, introduced by Do and Thiele, are isomorphic to Banach spaces, and we show the expected duality properties between them for $1 < p \leq \infty, 1 \leq r < \infty$ or $p=r \in \{ 1, \infty \}$ uniformly in the finite setting. In the case $p=1, 1 < r \leq \infty$, we exhibit a counterexample to uniformity. We show that in the upper half space setting these properties hold true in the full range $1 \leq p,r \leq \infty$. These results are obtained via greedy decompositions of functions in $L^p_\mu(\ell^r)$. As a consequence, we establish the equivalence between the classical tent spaces $T^p_r$ and the outer $L^p_\mu(\ell^r)$ spaces in the upper half space. Finally, we give a full classification of weak and strong type estimates for a class of embedding maps to the upper half space with a fractional scale factor for functions on $\mathbb{R}^d$., Comment: 32 pages, 1 figure

We refine the definition of generalized Stummel classes and study inclusion properties of these classes. We also study the inclusion relation between Stummel classes and other function spaces such as generalized Morrey spaces, weak Morrey spaces, and Lorentz spaces. In addition, we show that these inclusions are proper. Our results extend some previous results in \cite{CRR, RZ}., 14 pages

We consider functions of vanishing mean oscillation on a bounded domain $\Omega$ and prove a $\rm{VMO}$ analogue of the extension theorem of P. Jones for $\rm{BMO}(\Omega)$. We show that if $\Omega$ satisfies the same condition imposed by Jones (i.e.\ is a uniform domain), there is a linear extension map from $\rm{VMO}(\Omega)$ to $\rm{VMO}(\mathbb{R}^n)$ which is bounded in the $\rm{BMO}$ norm. Moreover, if such an extension map exists from $\rm{VMO}(\Omega)$ to $\rm{BMO}(\mathbb{R}^n)$, then the domain is uniform., Comment: 26 pages

In this paper, we prove that the inclusions between Morrey spaces, between weak Morrey spaces, and between a Morrey space and a weak Morrey space are all proper. The proper inclusion between a Morrey space and a weak Morrey space is established via the unboundedness of the Hardy-Littlewood maximal operator on Morrey spaces of exponent 1. In addition, we also give a necessary condition for each inclusion. Our results refine previous inclusion properties studied in [Gunawan et al, \emph{Math. Nachr.} {\bf 290} (2017), 332--340]., 8 pages

In this paper, we introduce a new scale of tent spaces which covers, the (weighted) tent spaces of Coifman-Meyer-Stein and of Hofmann-Mayboroda-McIntosh, and some other tent spaces considered by Dahlberg, Kenig-Pipher and Auscher-Axelsson in elliptic equations. The strong factorizations within our tent spaces, with applications to quasi-Banach complex interpolation and to multiplier-duality theory, are established. This way, we unify and extend the corresponding results obtained by Coifman-Meyer-Stein, Cohn-Verbitsky and Hyt\"onen-Ros\'en., Comment: 20 pages. Comments are welcome