Translation invariant forms on L p ( G ) ( 1 < p < )

Jean Bourgain

Annales de l'institut Fourier (1986)

  • Volume: 36, Issue: 1, page 97-104
  • ISSN: 0373-0956

Abstract

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It is shown that if G is a connected metrizable compact Abelian group and 1 < p < , any (possibly discontinuous) translation invariant linear form on L p ( G ) is a scalar multiple of the Haar measure. This result extends the theorem of G.H. Meisters and W.M. Schmidt (J. Funct. Anal. 13 (1972), 407-424) on L 2 ( G ) . Our method permits in fact to consider any superreflexive translation invariant Banach lattice on G , which is the adopted point of view. We study the representation of an element f of this invariant lattice X as a sum of a bounded number of elements of the form g - τ ( a ) g , where g in X , a in G and τ ( a ) the corresponding translation operator. Our approach consists in proving the boundedness of certain random convolution operators using interpolation techniques.

How to cite

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Bourgain, Jean. "Translation invariant forms on $L^p(G)(1&lt;p&lt;\infty )$." Annales de l'institut Fourier 36.1 (1986): 97-104. <http://eudml.org/doc/74707>.

@article{Bourgain1986,
abstract = {It is shown that if $G$ is a connected metrizable compact Abelian group and $1&lt; p&lt; \infty $, any (possibly discontinuous) translation invariant linear form on $L^ p(G)$ is a scalar multiple of the Haar measure. This result extends the theorem of G.H. Meisters and W.M. Schmidt (J. Funct. Anal. 13 (1972), 407-424) on $L^ 2(G)$. Our method permits in fact to consider any superreflexive translation invariant Banach lattice on $G$, which is the adopted point of view. We study the representation of an element $f$ of this invariant lattice $X$ as a sum of a bounded number of elements of the form $g-\tau (a)g$, where $g$ in $X$, $a$ in $G$ and $\tau (a)$ the corresponding translation operator. Our approach consists in proving the boundedness of certain random convolution operators using interpolation techniques.},
author = {Bourgain, Jean},
journal = {Annales de l'institut Fourier},
keywords = {connected metrizable compact abelian group; translation invariant linear form; scalar multiple; Haar measure; boundedness; random convolution operators},
language = {eng},
number = {1},
pages = {97-104},
publisher = {Association des Annales de l'Institut Fourier},
title = {Translation invariant forms on $L^p(G)(1&lt;p&lt;\infty )$},
url = {http://eudml.org/doc/74707},
volume = {36},
year = {1986},
}

TY - JOUR
AU - Bourgain, Jean
TI - Translation invariant forms on $L^p(G)(1&lt;p&lt;\infty )$
JO - Annales de l'institut Fourier
PY - 1986
PB - Association des Annales de l'Institut Fourier
VL - 36
IS - 1
SP - 97
EP - 104
AB - It is shown that if $G$ is a connected metrizable compact Abelian group and $1&lt; p&lt; \infty $, any (possibly discontinuous) translation invariant linear form on $L^ p(G)$ is a scalar multiple of the Haar measure. This result extends the theorem of G.H. Meisters and W.M. Schmidt (J. Funct. Anal. 13 (1972), 407-424) on $L^ 2(G)$. Our method permits in fact to consider any superreflexive translation invariant Banach lattice on $G$, which is the adopted point of view. We study the representation of an element $f$ of this invariant lattice $X$ as a sum of a bounded number of elements of the form $g-\tau (a)g$, where $g$ in $X$, $a$ in $G$ and $\tau (a)$ the corresponding translation operator. Our approach consists in proving the boundedness of certain random convolution operators using interpolation techniques.
LA - eng
KW - connected metrizable compact abelian group; translation invariant linear form; scalar multiple; Haar measure; boundedness; random convolution operators
UR - http://eudml.org/doc/74707
ER -

References

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  1. [1] A. CONNES, Private communication. 
  2. [2] B. JOHNSON, A proof of the translation invariant form conjecture for L²(G), Bull. de Sciences Math., 107, n° 3, (1983), 301-310. Zbl0529.43003MR85k:43003
  3. [3] J. LINDENSTRAUSS, L. TZAFRIRI, Classical Banach spaces II, Springer, 97 (1979). Zbl0403.46022MR81c:46001
  4. [4] G.H. MEISTERS, W.M. SCHMIDT, Translation invariant linear forms on L²(G) for compact Abelian group G, J. Funct. Anal., n° 13, (1972), 407-424. Zbl0247.43004
  5. [5] G. PISIER, Some applications of the complex interpolation method to Banach lattices, J. d'Analyse Math. de Jérusalem, Vol 35 (1979), 264-281. Zbl0427.46048MR80m:46020
  6. [6] J. BERGH, J. LOFSTRÖM, Interpolation Spaces. 

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