{ "id": "1701.08922", "version": "v1", "published": "2017-01-31T05:32:09.000Z", "updated": "2017-01-31T05:32:09.000Z", "title": "Hardy-Littlewood inequalities on compact quantum groups of Kac type", "authors": [ "SangGyun Youn" ], "comment": "22 pages", "categories": [ "math.OA" ], "abstract": "The Hardy-Littlewood inequality on $\\mathbb{T}$ compares the $L^p$-norm of a function with a weighted $\\ell^p$-norm of its Fourier coefficients. The approach has recently been studied for compact homogeneous spaces and we study a natural analogue in the framework of compact quantum groups. Especially, in the case of the reduced group $C^*$-algebras and free quantum groups, we establish explicit $L^p-\\ell^p$ inequalities through inherent information of underlying quantum group, such as growth rate and rapid decay property. Moreover, we show sharpness of the inequalities in a large class, including $C(G)$ with compact Lie group, $C_r^*(G)$ with polynomially growing discrete group and free quantum groups $O_N^+$, $S_N^+$.", "revisions": [ { "version": "v1", "updated": "2017-01-31T05:32:09.000Z" } ], "analyses": { "subjects": [ "20G42", "46L52" ], "keywords": [ "compact quantum groups", "hardy-littlewood inequality", "kac type", "free quantum groups", "compact lie group" ], "note": { "typesetting": "TeX", "pages": 22, "language": "en", "license": "arXiv", "status": "editable" } } }