English

Continuous generalization of Clarkson-McCarthy inequalities

Functional Analysis 2018-01-09 v1

Abstract

Let GG be a compact abelian group, let μ\mu be the corresponding Haar measure, and let G^\hat G be the Pontryagin dual of GG. Further, let CpC_p denote the Schatten class of operators on some separable infinite dimensional Hilbert space, and let Lp(G;Cp)L^p(G;C_p) denote the corresponding Bochner space. If GθAθG\ni\theta\mapsto A_\theta is the mapping belonging to Lp(G;Cp)L^p(G;C_p) then, kG^Gk(θ)AθdθppGAθppdθ,p2\sum_{k\in\hat G}\left\|\int_G\overline{k(\theta)}A_\theta\,\mathrm{d}\theta\right\|_p^p\le\int_G\|A_\theta\|_p^p\,\mathrm{d}\theta,\qquad p\ge2 kG^Gk(θ)Aθdθpp(GAθpqdθ)p/q,p2.\sum_{k\in\hat G}\left\|\int_G\overline{k(\theta)}A_\theta\,\mathrm{d}\theta\right\|_p^p\le\left(\int_G\|A_\theta\|_p^q\,\mathrm{d}\theta\right)^{p/q},\qquad p\ge2. kG^Gk(θ)Aθdθpq(GAθppdθ)q/p,p2.\sum_{k\in\hat G}\left\|\int_G\overline{k(\theta)}A_\theta\,\mathrm{d}\theta\right\|_p^q\le\left(\int_G\|A_\theta\|_p^p\,\mathrm{d}\theta\right)^{q/p},\qquad p\le2. If GG is a finite group, the previous comprises several earlier obtained generalizations of Clarkson-McCarthy inequalities (e.g. G=ZnG=\mathbf{Z}_n or G=Z2nG=\mathbf{Z}_2^n), as well as the original inequalities, for G=Z2G=\mathbf{Z}_2. Other related inequalities are also obtained.

Keywords

Cite

@article{arxiv.1801.02103,
  title  = {Continuous generalization of Clarkson-McCarthy inequalities},
  author = {Dragoljub J. Kečkić},
  journal= {arXiv preprint arXiv:1801.02103},
  year   = {2018}
}
R2 v1 2026-06-22T23:38:20.224Z