This is an announcement for the paper "Non-commutative Khintchine type
inequalities associated with free groups" by Javier Parcet and Gilles
Pisier.
Abstract: Let Fn denote the free group with n generators g1,g2,..,gn. Let
$\lambda$ stand for the left regular representation of Fn and let $\tau$
be the standard trace associated to $\lambda$. Given any positive integer
d, we study the operator space structure of the subspace Wp(n,d) of
Lp(\tau) generated by the family of operators $\lambda(g_{i_1}g_{i_2}
... g_{i_d})$ with $1 \le i_k \le n$. Moreover, our description of this
operator space holds up to a constant which does not depend on n or p,
so that our result remains valid for infinitely many generators. We
also consider the subspace of L_p(\tau) generated by the image under
$\lambda$ of the set of reduced words of length d. Our result extends
to any exponent $1 \le p \le \infty$ a previous result of Buchholz for
the space $W_{\infty}(n,d)$.
Archive classification: Operator Algebras; Functional Analysis
Mathematics Subject Classification: 46L52; 46L53
Remarks: 19 pages
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Submitted from: javier.parcet(a)uam.es
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This is an announcement for the paper "A generalization of the
Markov-Kakutani fixed point theorem" by Jaroslaw Wawrzycki.
Abstract: In this announcement we generalize the Markov-Kakutani fixed
point theorem for abelian semi-groups of affine transformations extending
it on some class of non-commutative semi-groups. As an interesting example
we apply it obtaining a generalization of the invariant version of the
Hahn-Banach theorem.
Archive classification: Functional Analysis
Mathematics Subject Classification: 46A22, 46A55
Remarks: 5 pages, Latex preparation
The source file(s), kakutani.tex: 11176 bytes, is(are) stored in gzipped
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Submitted from: Jaroslaw.Wawrzycki(a)ifj.edu.pl
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This is an announcement for the paper "Weakly null sequences in the
Banach space C(K)" by I. Gasparis, E. Odell, and B. Wahl.
Abstract: The hierarchy of the block bases of transfinite normalized
averages of a normalized Schauder basic sequence is introduced and a
criterion is given for a normalized weakly null sequence in C(K), the
Banach space of scalar valued functions continuous on the compact metric
space K, to admit a block basis of normalized averages equivalent to the
unit vector basis of c_0, the Banach space of null scalar sequences. As
an application of this criterion, it is shown that every normalized
weakly null sequence in C(K), for countable K, admits a block basis of
normalized averages equivalent to the unit vector basis of c_0.
Archive classification: Functional Analysis
Mathematics Subject Classification: 46B03
Remarks: 36 pages
The source file(s), gow5.tex: 137843 bytes, is(are) stored in gzipped
form as 0402202.gz with size 33kb. The corresponding postcript file has
gzipped size 147kb.
Submitted from: combs(a)mail.ma.utexas.edu
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This is an announcement for the paper "A classification for 2-isometries
of noncommutative Lp-spaces" by Marius Junge, Zhong-Jin Ruan and David
Sherman.
Abstract: In this paper we extend previous results of Banach, Lamperti
and Yeadon on isometries of Lp-spaces to the non-tracial case first
introduced by Haagerup. Specifically, we use operator space techniques
and an extrapolation argument to prove that every 2-isometry T : Lp(M)
to Lp(N) between arbitrary noncommutative Lp-spaces can always be written
in the form T(phi^{1/p}) = w (phi circ pi^{-1} circ E)^{1/p}, for phi
in M_*^+. Here pi is a normal *-isomorphism from M onto the von Neumann
subalgebra pi(M) of N, w is a partial isometry in N, and E is a normal
conditional expectation from N onto pi(M). As a consequence of this,
any 2-isometry is automatically a complete isometry and has completely
contractively complemented range.
Archive classification: Operator Algebras
Remarks: 25 pages
The source file(s), 2isom.tex: 88005 bytes, is(are) stored in gzipped
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Submitted from: dasherma(a)ux1.cso.uiuc.edu
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FUNCTIONAL ANALYSIS WORKSHOP
JOENSUU, FINLAND
June 20.-24., 2004
The workshop is a satellite conference of the 4th European Congress of Mathematics
(4ecm) in Stockholm. The topics of this workshop include Banach spaces and operator
theory, Frechet and related spaces, and applications to analytic function spaces.
There will be 13 invited plenary lectures and, in addition, shorter talks by
the participants. Main plenary lectures will be given by:
Klaus Bierstedt (Paderborn)
Jose Bonet (Valencia)
Alexander Borichev (Bordeaux)
Gilles Godefroy (Paris)
Chen Huaihui (Nanjing)
Serguei Kislyakov (St. Petersburg)
Reinhold Meise (Dusseldorf)
Artur Nicolau (Barcelona)
Edward Odell (Austin)
David Preiss (London)
Eero Saksman (Jyvaskyla)
Joel Shapiro (East Lansing)
Dietmar Vogt (Wuppertal)
Scientific committee: Jari Taskinen (Joensuu, chair), Rauno Aulaskari (Joensuu),
Mikael Lindstr\"om (Abo), Hans-Olav Tylli (Helsinki).
Joensuu is a pleasant mid-size town in eastern Finland, which is conveniently
accessible from Helsinki by frequent trains or flights. The scientific programme
of the workshop will commence on the morning of June 21.
More information about the workshop (registration, programme, accommodation,
contact addresses, location) can be found on the www-page
http://www.joensuu.fi/mathematics/workshop2004
This is an announcement for the paper "On Fr\'echet differentiability
of Lipschitz maps between Banach spaces" by Joram Lindenstrauss and
David Preiss.
Abstract: A well-known open question is whether every countable collection
of Lipschitz functions on a Banach space X with separable dual has a
common point of Frechet differentiability. We show that the answer is
positive for some infinite-dimensional X. Previously, even for collections
consisting of two functions this has been known for finite-dimensional X
only (although for one function the answer is known to be affirmative
in full generality). Our aims are achieved by introducing a new
class of null sets in Banach spaces (called $\Gamma$-null sets),
whose definition involves both the notions of category and measure,
and showing that the required differentiability holds almost everywhere
with respect to it. We even obtain existence of Fr\'echet derivatives
of Lipschitz functions between certain infinite-dimensional Banach
spaces;no such results have been known previously. Our main result
states that a Lipschitz map between separable Banach spaces is Fr\'echet
differentiable $\Gamma$-almost everywhere provided that it is regularly
Gateaux differentiable $\Gamma$-almost everywhere and the Gateaux
derivatives stay within a norm separable space of operators. It is
easy to see that Lipschitz maps of X to spaces with the Radon-Nikodym
property are Gateaux differentiable $\Gamma$-almost everywhere. Moreover,
Gateaux differentiability implies regular Gateaux differentiability with
exception of another kind of negligible sets, so-called $\sigma$-porous
sets. The answer to the question is therefore positive in every space
in which every $\sigma$-porous set is $\Gamma$-null. We show that this
holds for $C(K)$ with $K$ countable compact, the Tsirelson space and
for all subspaces of $c_0$, but that it fails for Hilbert spaces.
Archive classification: Functional Analysis
Citation: Ann. of Math. (2), Vol. 157 (2003), no. 1, 257--288
Remarks: 32 pages, published version
The source file(s), amlts.sty: 33990 bytes, lindenstrauss.tex: 89631
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Submitted from: dp(a)math.ucl.ac.uk
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This is an announcement for the paper "An analogue of the Fuglede formula
in integral geometry on matrix spaces" by E.Ournycheva and B.Rubin.
Abstract: The well known formula of B. Fuglede expresses the mean value
of the Radon k-plane transform on $R^n$ as a Riesz potential. We extend
this formula to the space of $n \times m$ real matrices and show that
the corresponding matrix k-plane transform $f \to \hat f$ is injective
if and only if
$n-k \ge m$. Different inversion formulas for this transform are
obtained. We
assume that $f \in L^p$ or $f$ is a continuous function satisfying certain
"minimal" conditions at infinity.
Archive classification: Functional Analysis
Mathematics Subject Classification: Primary 44A12; Secondary 47G10
Remarks: AMS LaTeX, 20 pages
The source file(s), Fug8.tex: 50342 bytes, is(are) stored in gzipped
form as 0401127.gz with size 18kb. The corresponding postcript file has
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Submitted from: ournyce(a)math.huji.ac.il
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This is an announcement for the paper "On the interpolation of injective
or projective tensor products of Banach spaces" by Omran Kouba.
Abstract: We prove a general result on the factorization of matrix-valued
analytic functions. We deduce that if $(E_0,E_1)$ and $(F_0,F_1)$ are
interpolation pairs with dense intersections, then under some conditions
on the spaces $E_0$, $E_1$, $F_0$ and $F_1$, we have $$ [E_0\hat\otimes
F_0,E_1\hat\otimes F_1]_t= [E_0 ,E_1]_t\hat\otimes[F_0 ,F_1]_t, 0 <
t< 1.$$
We find also conditions on the spaces $E_0$, $E_1$, $F_0$ and $F_1$,
so that
the following holds $$ [E_0\wcheck\otimes F_0,E_1\wcheck\otimes F_1]_t=
[E_0,E_1]_t\wcheck\otimes [F_0,F_1]_t, 0 <t< 1.$$
Some applications of these results are also considered.
Archive classification: Functional Analysis
Mathematics Subject Classification: 46B70;47A56;47A68;46M05;46B07
Citation: J. Funct. Anal. 96 (1991), 38-61
Remarks: 26 pages
The source file(s), ART3.Tex: 75244 bytes, is(are) stored in gzipped
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Submitted from: omran_kouba(a)hiast.edu.sy
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This is an announcement for the paper "L'Application canonique $J:H^2(X)
\otimes H^2(X)->H^1(X\otimes X)$ n'est pas surjective en g\'en\'eral"
by Omran Kouba.
Abstract: We introduce the $H^1$-projective property, and use it to
construct a Banach space $X$ such that the natural map
$J:H^2(X)\otimes H^2(X) -> H^1(X\otimes X)$ is not onto.
Archive classification: Functional Analysis
Mathematics Subject Classification: 46M05;47A56;47A68
Citation: C.R. Acad. Sci. Paris t.307, Serie I, (1988), 949-953
Remarks: 9 pages, French with abridged english version
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Submitted from: omran_kouba(a)hiast.edu.sy
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This is an announcement for the paper "An isomorphic version of the
slicing problem" by B. Klartag.
Abstract: Here we show that any n-dimensional centrally symmetric convex
body K has an n-dimensional perturbation T which is convex and centrally
symmetric, such that the isotropic constant of T is universally bounded. T
is close to K in the sense that the Banach-Mazur distance between T
and K is O(log n). If K has a non-trivial type then the distance is
universally bounded. In addition, if K is quasi-convex then there exists
a quasi-convex T with a universally bounded isotropic constant and with
a universally bounded distance to K.
Archive classification: Metric Geometry; Functional Analysis
Remarks: 19 pages
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Submitted from: klartagb(a)post.tau.ac.il
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