This is an announcement for the paper "Positive definite functions and
multidimensional versions of random variables" by Alexander Koldobsky.
Abstract: We say that a random vector $X=(X_1,...,X_n)$ in $R^n$ is an
$n$-dimensional version of a random variable $Y$ if for any $a\in R^n$
the random variables $\sum a_iX_i$ and $\gamma(a) Y$ are identically
distributed, where $\gamma:R^n\to [0,\infty)$ is called the standard
of $X.$ An old problem is to characterize those functions $\gamma$
that can appear as the standard of an $n$-dimensional version. In this
paper, we prove the conjecture of Lisitsky that every standard must be
the norm of a space that embeds in $L_0.$ This result is almost optimal,
as the norm of any finite dimensional subspace of $L_p$ with $p\in (0,2]$
is the standard of an $n$-dimensional version ($p$-stable random vector)
by the classical result of P.L\`evy. An equivalent formulation is that if
a function of the form $f(\|\cdot\|_K)$ is positive definite on $R^n,$
where $K$ is an origin symmetric star body in $R^n$ and $f:R\to R$ is
an even continuous function, then either the space $(R^n,\|\cdot\|_K)$
embeds in $L_0$ or $f$ is a constant function. Combined with known facts
about embedding in $L_0,$ this result leads to several generalizations
of the solution of Schoenberg's problem on positive definite functions.
Archive classification: math.PR math.FA
Mathematics Subject Classification: 60E05
The source file(s), posdef1.tex: 32112 bytes, is(are) stored in gzipped
form as 0903.1433.gz with size 10kb. The corresponding postcript file
has gzipped size 86kb.
Submitted from: koldobskiya(a)missouri.edu
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This is an announcement for the paper "Weakly countably determined spaces
of high complexity" by Antonio Aviles.
Abstract: We prove that there exist weakly countably determined spaces
of complexity higher than coanalytic. On the other hand, we also show
that coanalytic sets can be characterized by the existence of a cofinal
adequate family of closed sets. Therefore the Banach spaces constructed
by means of these families have at most coanalytic complexity.
Archive classification: math.FA
Mathematics Subject Classification: 46B26
Citation: Stud. Math. 185, No. 3, 291-303 (2008)
Remarks: This version differs from the published in Studia Mathematica
in that
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/0903.0852
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This is an announcement for the paper "Cotype and absolutely summing
linear operators" by Geraldo Botelho, Daniel Pellegrino and Pilar Rueda.
Abstract: Cotype is used in this paper to prove new results concerning
the existence of non-absolutely summing linear operators between Banach
spaces. We derive consequences that extend/generalize/ complement some
classic results. We also point out that some of our results are sharp.
Archive classification: math.FA
Mathematics Subject Classification: 46G25, 45B20
Remarks: 8 pages
The source file(s), linear_results03March2009-without.tex: 40121 bytes,
is(are) stored in gzipped form as 0903.0583.gz with size 12kb. The
corresponding postcript file has gzipped size 78kb.
Submitted from: dmpellegrino(a)gmail.com
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This is an announcement for the paper "The Schur l1 Theorem for filters"
by Antonio Aviles, Bernardo Cascales, Vladimir Kadets, and Alexander
Leonov.
Abstract: We study the classes of filters F on N such that the weak
and strong F-convergence of sequences in l1 coincide. We study also
an analogue of l1 weak sequential completeness theorem for filter
convergence.
Archive classification: math.FA math.GN
Citation: Journal of Mathematical Physics, Analysis, Geometry: 2007, v. 3,
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/0903.0659
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This is an announcement for the paper "Automorphisms in spaces of
continuous functions on Valdivia compacta" by Antonio Aviles and Yolanda
Moreno.
Abstract: We show that there are no automorphic Banach spaces of the
form C(K) with K continuous image of Valdivia compact except the spaces
c0(I). Nevertheless, when K is an Eberlein compact of finite height such
that C(K) is not isomorphic to c0(I), all isomorphism between subspaces
of C(K) of size less than aleph_omega extend to automorphisms of C(K).
Archive classification: math.FA math.GN
Mathematics Subject Classification: 46B26
Citation: Topology Appl. 155, No. 17-18, 2027-2030 (2008)
The source file(s), AutomorficosValdivia.tex: 19190 bytes, is(are)
stored in gzipped form as 0903.0658.gz with size 7kb. The corresponding
postcript file has gzipped size 61kb.
Submitted from: avileslo(a)um.es
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/0903.0658
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This is an announcement for the paper "Expansion properties of metric
spaces not admitting a coarse embedding into a Hilbert space" by
M.I. Ostrovskii.
Abstract: The main purpose of the paper is to find some expansion
properties of locally finite metric spaces which do not embed coarsely
into a Hilbert space. The obtained result is used to show that infinite
locally finite graphs excluding a minor embed coarsely into a Hilbert
space. In an appendix a direct proof of the latter result is given.
Archive classification: math.MG math.FA
Mathematics Subject Classification: 46B20; 05C12; 54E35
The source file(s), ExpansionArXivversion.tex: 22813 bytes, is(are)
stored in gzipped form as 0903.0607.gz with size 8kb. The corresponding
postcript file has gzipped size 80kb.
Submitted from: ostrovsm(a)stjohns.edu
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This is an announcement for the paper "Countable products of spaces of
finite sets" by Antonio Aviles.
Abstract: We consider the compact spaces sigma_n(I) of subsets of
an uncountable set I of cardinality at most n and their countable
products. We give a complete classification of their Banach spaces of
continuous functions and a partial topological classification.
Archive classification: math.GN math.FA
Mathematics Subject Classification: 46B50, 46B26, 54B10, 54D30
Citation: Fundamenta Math. 186, No. 2, 147-159 (2005)
The source file(s), SigmakProducts.tex: 40152 bytes, is(are) stored in
gzipped form as 0903.0068.gz with size 12kb. The corresponding postcript
file has gzipped size 102kb.
Submitted from: avileslo(a)um.es
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/0903.0068
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This is an announcement for the paper "The number of weakly compact sets
which generate a Banach space" by Antonio Aviles.
Abstract: We consider the cardinal invariant CG(X) of the minimal number
of weakly compact subsets which generate a Banach space X. We study the
behavior of this index when passing to subspaces, its relation with the
Lindelof number in the weak topology and other related questions.
Archive classification: math.FA math.GN
Citation: Israel J. Math. 159, 189-204 (2007)
The source file(s), CGX.tex: 47171 bytes, is(are) stored in gzipped
form as 0903.0063.gz with size 15kb. The corresponding postcript file
has gzipped size 94kb.
Submitted from: avileslo(a)um.es
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/0903.0063
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This is an announcement for the paper "The number of weakly compact
convex subsets of the Hilbert space" by Antonio Aviles.
Abstract: We prove that for k an uncountable cardinal, there exist 2^k
many non homeomorphic weakly compact convex subsets of weight k in the
Hilbert space of density k.
Archive classification: math.GN math.FA
Mathematics Subject Classification: 54B35, 52A07
Citation: Topology Appl. 155, No. 15, 1720-1725 (2008)
The source file(s), Manyconvex.tex: 28889 bytes, is(are) stored in
gzipped form as 0903.0163.gz with size 9kb. The corresponding postcript
file has gzipped size 71kb.
Submitted from: avileslo(a)um.es
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/0903.0163
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This is an announcement for the paper "Renormings of the dual of James
tree spaces" by Antonio Aviles.
Abstract: We discuss renorming properties of the dual of a James tree
space JT. We present examples of weakly Lindelof determined JT such that
JT* admits neither strictly convex nor Kadec renorming and of weakly
compactly generated JT such that JT* does not admit Kadec renorming
although it is strictly convexifiable.
Archive classification: math.FA
Mathematics Subject Classification: 46B26
Citation: Bull. Lond. Math. Soc. 39, No. 2, 221-231 (2007)
The source file(s), RosenthalLUR.tex: 41974 bytes, is(are) stored in
gzipped form as 0903.0158.gz with size 13kb. The corresponding postcript
file has gzipped size 91kb.
Submitted from: avileslo(a)um.es
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http://front.math.ucdavis.edu/0903.0158
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