{ "id": "2307.09859", "version": "v1", "published": "2023-07-19T09:42:28.000Z", "updated": "2023-07-19T09:42:28.000Z", "title": "A variant of Hilbert's inequality and the norm of the Hilbert Matrix on $K^p$", "authors": [ "Vassilis Daskalogiannis", "Petros Galanopoulos", "Michael Papadimitrakis" ], "comment": "14 pages", "categories": [ "math.FA" ], "abstract": "We prove the nontrivial variant \\[ \\sum\\limits_{m,n=1}^{\\infty}\\Big(\\frac{n}{m}\\Big)^{\\frac{1}{q}-\\frac{1}{p}}\\frac{a_mb_n}{m+n-1}\\leq\\frac{\\pi}{\\sin\\frac{\\pi}{p}} \\Big( \\sum\\limits_{m=1}^{\\infty}a_m^p\\Big)^{\\frac 1p}\\Big( \\sum\\limits_{n=1}^{\\infty}b_n^q\\Big)^{\\frac 1q} \\] of the well known Hilbert's inequality. Then we use this to determine the exact value $\\frac{\\pi}{\\sin\\frac{\\pi}p}$ of the norm of the Hilbert matrix as an operator acting on the Hardy-Littlewood space $K^p$. This space consists of all functions $f(z)=\\sum\\limits_{m=0}^{\\infty}a_mz^m$ analytic in the unit disc with $\\|f\\|_{K^p}^p=\\sum\\limits_{m=0}^{\\infty}(m+1)^{p-2}|a_m|^p<+\\infty$.", "revisions": [ { "version": "v1", "updated": "2023-07-19T09:42:28.000Z" } ], "analyses": { "subjects": [ "47A30", "47B37", "47B91" ], "keywords": [ "hilbert matrix", "hilberts inequality", "unit disc", "nontrivial variant", "space consists" ], "note": { "typesetting": "TeX", "pages": 14, "language": "en", "license": "arXiv", "status": "editable" } } }