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Embeddings of Müntz Spaces in $L^{\infty }(\unicode[STIX]{x1D707})$

Published online by Cambridge University Press:  09 January 2019

Ihab Al Alam
Affiliation:
Lebanese University, Faculty of Sciences II, Department of Mathematics, Fanar-Matn 90656, Lebanon Email: ihabalam@yahoo.fr
Pascal Lefèvre
Affiliation:
Laboratoire de Mathématiques de Lens, Université Artois, 62307 Lens, France Email: pascal.lefevre@univ-artois.fr
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Abstract

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In this paper, we discuss the properties of the embedding operator $i_{\unicode[STIX]{x1D707}}^{\unicode[STIX]{x1D6EC}}:M_{\unicode[STIX]{x1D6EC}}^{\infty }{\hookrightarrow}L^{\infty }(\unicode[STIX]{x1D707})$, where $\unicode[STIX]{x1D707}$ is a positive Borel measure on $[0,1]$ and $M_{\unicode[STIX]{x1D6EC}}^{\infty }$ is a Müntz space. In particular, we compute the essential norm of this embedding. As a consequence, we recover some results of the first author. We also study the compactness (resp. weak compactness) and compute the essential norm (resp. generalized essential norm) of the embedding $i_{\unicode[STIX]{x1D707}_{1},\unicode[STIX]{x1D707}_{2}}:L^{\infty }(\unicode[STIX]{x1D707}_{1}){\hookrightarrow}L^{\infty }(\unicode[STIX]{x1D707}_{2})$, where $\unicode[STIX]{x1D707}_{1}$, $\unicode[STIX]{x1D707}_{2}$ are two positive Borel measures on [0, 1] with $\unicode[STIX]{x1D707}_{2}$ absolutely continuous with respect to $\unicode[STIX]{x1D707}_{1}$.

Type
Article
Copyright
© Canadian Mathematical Society 2018 

Footnotes

This work is part of the project CEDRE ESFO. The authors would like to thank the program PHC CEDRE and the Lebanese University for their support.

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