Semivariation in L p -spaces

Brian Jefferies; Susumu Okada

Commentationes Mathematicae Universitatis Carolinae (2005)

  • Volume: 46, Issue: 3, page 425-436
  • ISSN: 0010-2628

Abstract

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Suppose that X and Y are Banach spaces and that the Banach space X ^ τ Y is their complete tensor product with respect to some tensor product topology τ . A uniformly bounded X -valued function need not be integrable in X ^ τ Y with respect to a Y -valued measure, unless, say, X and Y are Hilbert spaces and τ is the Hilbert space tensor product topology, in which case Grothendieck’s theorem may be applied. In this paper, we take an index 1 p < and suppose that X and Y are L p -spaces with τ p the associated L p -tensor product topology. An application of Orlicz’s lemma shows that not all uniformly bounded X -valued functions are integrable in X ^ τ p Y with respect to a Y -valued measure in the case 1 p < 2 . For 2 < p < , the negative result is equivalent to the fact that not all continuous linear maps from 1 to p are p -summing, which follows from a result of S. Kwapien.

How to cite

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Jefferies, Brian, and Okada, Susumu. "Semivariation in $L^p$-spaces." Commentationes Mathematicae Universitatis Carolinae 46.3 (2005): 425-436. <http://eudml.org/doc/249537>.

@article{Jefferies2005,
abstract = {Suppose that $X$ and $Y$ are Banach spaces and that the Banach space $X\hat\{\otimes \}_\tau Y$ is their complete tensor product with respect to some tensor product topology $\tau $. A uniformly bounded $X$-valued function need not be integrable in $X\hat\{\otimes \}_\tau Y$ with respect to a $Y$-valued measure, unless, say, $X$ and $Y$ are Hilbert spaces and $\tau $ is the Hilbert space tensor product topology, in which case Grothendieck’s theorem may be applied. In this paper, we take an index $1 \le p < \infty $ and suppose that $X$ and $Y$ are $L^p$-spaces with $\tau _p$ the associated $L^p$-tensor product topology. An application of Orlicz’s lemma shows that not all uniformly bounded $X$-valued functions are integrable in $X\hat\{\otimes \}_\{\tau _p\} Y$ with respect to a $Y$-valued measure in the case $1\le p < 2$. For $2 < p <\infty $, the negative result is equivalent to the fact that not all continuous linear maps from $\ell ^1$ to $\ell ^p$ are $p$-summing, which follows from a result of S. Kwapien.},
author = {Jefferies, Brian, Okada, Susumu},
journal = {Commentationes Mathematicae Universitatis Carolinae},
keywords = {absolutely $p$-summing; bilinear integration; semivariation; tensor product; absolutely -summing; bilinear integration; semivariation; tensor product},
language = {eng},
number = {3},
pages = {425-436},
publisher = {Charles University in Prague, Faculty of Mathematics and Physics},
title = {Semivariation in $L^p$-spaces},
url = {http://eudml.org/doc/249537},
volume = {46},
year = {2005},
}

TY - JOUR
AU - Jefferies, Brian
AU - Okada, Susumu
TI - Semivariation in $L^p$-spaces
JO - Commentationes Mathematicae Universitatis Carolinae
PY - 2005
PB - Charles University in Prague, Faculty of Mathematics and Physics
VL - 46
IS - 3
SP - 425
EP - 436
AB - Suppose that $X$ and $Y$ are Banach spaces and that the Banach space $X\hat{\otimes }_\tau Y$ is their complete tensor product with respect to some tensor product topology $\tau $. A uniformly bounded $X$-valued function need not be integrable in $X\hat{\otimes }_\tau Y$ with respect to a $Y$-valued measure, unless, say, $X$ and $Y$ are Hilbert spaces and $\tau $ is the Hilbert space tensor product topology, in which case Grothendieck’s theorem may be applied. In this paper, we take an index $1 \le p < \infty $ and suppose that $X$ and $Y$ are $L^p$-spaces with $\tau _p$ the associated $L^p$-tensor product topology. An application of Orlicz’s lemma shows that not all uniformly bounded $X$-valued functions are integrable in $X\hat{\otimes }_{\tau _p} Y$ with respect to a $Y$-valued measure in the case $1\le p < 2$. For $2 < p <\infty $, the negative result is equivalent to the fact that not all continuous linear maps from $\ell ^1$ to $\ell ^p$ are $p$-summing, which follows from a result of S. Kwapien.
LA - eng
KW - absolutely $p$-summing; bilinear integration; semivariation; tensor product; absolutely -summing; bilinear integration; semivariation; tensor product
UR - http://eudml.org/doc/249537
ER -

References

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  9. Jefferies B., Okada S., Bilinear integration in tensor products, Rocky Mountain J. Math. 28 2 (1998), 517-545. (1998) Zbl0936.46035MR1651584
  10. Kwapien S., On a theorem of L. Schwartz and its application to absolutely summing operators, Studia Math. 38 (1970), 193-201. (1970) MR0278090
  11. Lindenstrauss J., Tzafriri L., Classical Banach spaces I. Sequence Spaces, Springer, Berlin, New York, 1977. Zbl0362.46013MR0500056
  12. Schaefer H.H., Zhang X.-D., A note on bounded vector measures, Arch. Math. 23 (1994), 152-157. (1994) MR1289297
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