Abstract
We present a self-contained proof of the following famous extension theorem due to Carl Herz. A closed subgroup $H$ of a locally compact group $G$ is a set of $p$-synthesis in $G$ if and only if, for every $u\in A_p(H)\cap C_{00}(H)$ and for every $\varepsilon > 0$, there is $v\in A_p(G)\cap C_{00}(G)$, an extension of $u$, such that \[\|v\|_{A_p(G)} < \|u\|_{A_p(H)}+\varepsilon.\]
Citation
Antoine Derighetti. "On Herz's extension theorem." Adv. Oper. Theory 4 (2) 529 - 538, Spring 2019. https://doi.org/10.15352/aot.1809-1417
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