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Spaces of Lorentz Multipliers

Published online by Cambridge University Press:  20 November 2018

Kathryn E. Hare
Affiliation:
Dept. of Pure Mathematics Univ. of Waterloo Waterloo, Ont. N2L 3G1, email: [email protected]
Enji Sato
Affiliation:
Dept. of Mathematical Sciences Faculty of Science Yamagata University Yamagata 990-8560 Japan, email: [email protected]
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Abstract

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We study when the spaces of Lorentz multipliers from ${{L}^{p,t\,}}\to \,{{L}^{p,s}}$ are distinct. Our main interest is the case when $s\,<\,t$, the Lorentz-improving multipliers. We prove, for example, that the space of multipliers which map ${{L}^{p,t\,}}\to \,{{L}^{p,s}}$ is different from those mapping ${{L}^{r,v}}\,\to \,{{L}^{r,u}}$ if either $r\,=\,p$ or ${p}'$ and $1/s\,-\,1/t\,\ne \,1/u\,-\,1/v$, or $r\,\ne \,p$ or ${p}'$. These results are obtained by making careful estimates of the Lorentz multiplier norms of certain linear combinations of Fejer or Dirichlet kernels. For the case when the first indices are different the linear combination we analyze is in the spirit of a Rudin-Shapiro polynomial.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 2001

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