This is an announcement for the paper "Convex-transitivity of Banach
algebras via ideals" by Jarno Talponen.
Abstract: We investigate a method for producing concrete convex-transitive
Banach spaces. The gist of the method is in getting rid of dissymmetries
of a given space by taking a carefully chosen quotient. The spaces of
interest here are typically Banach algebras and their ideals. We also
investigate the convex-transitivity of ultraproducts and tensor products
of Banach spaces.
Archive classification: math.FA
Mathematics Subject Classification: 46B04, 47L20, 46Mxx, 47L10
Remarks: 18 pages
Submitted from: talponen(a)cc.hut.fi
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1106.1292
or
http://arXiv.org/abs/1106.1292
This is an announcement for the paper "Reconstruction from anisotropic
random measurements" by Mark Rudelson and Shuheng Zhou.
Abstract: Random matrices are widely used in sparse recovery problems,
and the relevant properties of matrices with i.i.d. entries are
well understood. The current paper discusses the recently introduced
Restricted Eigenvalue (RE) condition, which is among the most general
assumptions on the matrix, guaranteeing recovery. We prove a reduction
principle showing that the RE condition can be guaranteed by checking the
restricted isometry on a certain family of low-dimensional subspaces. This
principle allows us to establish the RE condition for several broad
classes of random matrices with dependent entries, including random
matrices with subgaussian rows and non-trivial covariance structure,
as well as matrices with independent rows, and uniformly bounded entries.
Archive classification: math.ST cs.IT math.FA math.IT stat.TH
Report Number: Technical Report 522, University of Michigan, Department
of Statistics
Remarks: 30 Pages
Submitted from: szhou(a)cs.cmu.edu
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1106.1151
or
http://arXiv.org/abs/1106.1151
This is an announcement for the paper "Stochastic order characterization
of uniform integrability and tightness" by Lasse Leskela and Matti Vihola.
Abstract: We show that a family of random variables is uniformly
integrable if and only if it is stochastically bounded in the increasing
convex order by an integrable random variable. This result is complemented
by proving analogous statements for the strong stochastic order and
for power-integrable dominating random variables. Especially, we show
that whenever a family of random variables is stochastically bounded
by a p-integrable random variable for some p>1, there is no distinction
between the strong order and the increasing convex order. These results
also yield new characterizations of relative compactness in Wasserstein
and Prohorov metrics.
Archive classification: math.PR math.FA
Mathematics Subject Classification: 60E15, 60B10, 60F25
Remarks: 14 pages, 1 figure
Submitted from: lasse.leskela(a)iki.fi
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1106.0607
or
http://arXiv.org/abs/1106.0607
This is an announcement for the paper "Characterising subspaces of
Banach spaces with a Schauder basis having the shift property" by
Christian Rosendal.
Abstract: We give an intrinsic characterisation of the separable
reflexive Banach spaces that embed into separable reflexive spaces
with an unconditional basis all of whose normalised block sequences with
the same growth rate are equivalent. This uses methods of E. Odell and
T. Schlumprecht.
Archive classification: math.FA
Mathematics Subject Classification: 46B03
Submitted from: rosendal(a)math.uic.edu
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1106.0472
or
http://arXiv.org/abs/1106.0472
This is an announcement for the paper "On the second parameter of an $(m,
p)$-Isometry" by Philipp Hoffmann and Michael Mackey.
Abstract: A bounded linear operator $T$ on a Banach space $X$ is called
an $(m, p)$-isometry if it satisfies the equation $\sum_{k=0}^{m}(-1)^{k}
{m \choose k}\|T^{k}x\|^{p} = 0$, for all $x \in X$. In the first part of
this paper we study the structure which underlies the second parameter
of $(m, p)$-isometric operators. More precisely, we concentrate on
the question of determining conditions on $q \neq p$ for which an
$(m, p)$-isometry can be a $(\mu, q)$-isometry for some $\mu$. In
the second part we extend the definition of $(m, p)$-isometry, to
include $p=\infty$. We then study basic properties of these $(m,
\infty)$-isometries.
Archive classification: math.FA
Submitted from: philipp.hoffmann(a)ucdconnect.ie
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1106.0339
or
http://arXiv.org/abs/1106.0339
This is an announcement for the paper "$L_{p}[0,1] \setminus
\bigcup\limits_{q>p} L_{q}[0,1]$ is spaceable for every $p>0$" by
G. Botelho, V. V. Favaro, D. Pellegrino and J. B. Seoane-Sepulveda.
Abstract: In this short note we prove the result stated in the title;
that is, for every $p>0$ there exists an infinite dimensional closed
linear subspace of $L_{p}[0,1]$ every nonzero element of which does not
belong to $\bigcup\limits_{q>p} L_{q}[0,1]$. This answers in the positive
a question raised in 2010 by R. M. Aron on the spaceability of the above
sets (for both, the Banach and quasi-Banach cases). We also complete
some recent results from \cite{BDFP} for subsets of sequence spaces.
Archive classification: math.FA
Remarks: 3 pages
Submitted from: dmpellegrino(a)gmail.com
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1106.0309
or
http://arXiv.org/abs/1106.0309
This is an announcement for the paper "Smooth approximations of norms
in separable Banach spaces" by Petr Hajek and Jarno Talponen.
Abstract: Let X be a separable real Banach space having a k-times
continuously Fr\'{e}chet differentiable (i.e. C^k-smooth) norm where
k=1,...,\infty. We show that any equivalent norm on X can be approximated
uniformly on bounded sets by C^k-smooth norms.
Archive classification: math.FA math.AG
Mathematics Subject Classification: Primary 46B03, 46T20, Secondary
47J07, 14P20
Remarks: 10 pages
Submitted from: talponen(a)cc.hut.fi
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1105.6046
or
http://arXiv.org/abs/1105.6046
This is an announcement for the paper "Central points and measures and
dense subsets of compact metric spaces" by Piotr Niemiec.
Abstract: For every nonempty compact convex subset $K$ of a normed linear
space a (unique) point $c_K \in K$, called the generalized Chebyshev
center, is distinguished. It is shown that $c_K$ is a common fixed
point for the isometry group of the metric space $K$. With use of the
generalized Chebyshev centers, the central measure $\mu_X$ of an arbitrary
compact metric space $X$ is defined. For a large class of compact metric
spaces, including the interval $[0,1]$ and all compact metric groups,
another `central' measure is distinguished, which turns out to coincide
with the Lebesgue measure and the Haar one for the interval and a compact
metric group, respectively. An idea of distinguishing infinitely many
points forming a dense subset of an arbitrary compact metric space is
also presented.
Archive classification: math.FA
Mathematics Subject Classification: Primary 46S30, 47H10, Secondary
46A55, 46B50
Remarks: 13 pages
Submitted from: piotr.niemiec(a)uj.edu.pl
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1105.5706
or
http://arXiv.org/abs/1105.5706
This is an announcement for the paper "Borel equivalence relations
between \ell_1 and \ell_p" by Longyun Ding and Zhi Yin.
Abstract: In this paper, we show that, for each $p>1$, there are continuum
many Borel equivalence relations between $\Bbb R^\omega/\ell_1$ and $\Bbb
R^\omega/\ell_p$ ordered by $\le_B$ which are pairwise Borel incomparable.
Archive classification: math.LO math.FA
Mathematics Subject Classification: 03E15, 46F45
Remarks: 7 pages, submitted
Submitted from: dingly(a)nankai.edu.cn
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1105.4492
or
http://arXiv.org/abs/1105.4492
This is an announcement for the paper "Five basic lemmas for symmetric
tensor products of normed spaces" by Daniel Carando and Daniel Galicer.
Abstract: We give the symmetric version of five lemmas which are
essential for the theory of tensor products (and norms). These are:
the approximation, extension, embedding, density and local technique
lemmas. Some application of these tools to the metric theory of symmetric
tensor products and to the theory of polynomials ideals are given.
Archive classification: math.FA
Mathematics Subject Classification: 46M05, 46G25, 47L22
Remarks: 24 pages
Submitted from: dgalicer(a)dm.uba.ar
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/1105.3746
or
http://arXiv.org/abs/1105.3746