{ "id": "1708.09635", "version": "v1", "published": "2017-08-31T09:32:40.000Z", "updated": "2017-08-31T09:32:40.000Z", "title": "The radical of the bidual of a Beurling algebra", "authors": [ "Jared T. White" ], "comment": "17 pages", "categories": [ "math.FA" ], "abstract": "We prove that the bidual of a Beurling algebra on $\\mathbb{Z}$, considered as a Banach algebra with the first Arens product, can never be semisimple. We then show that ${\\rm rad\\,}(\\ell^{\\, 1}(\\oplus_{i=1}^\\infty \\mathbb{Z})\")$ contains nilpotent elements of every index. Each of these results settles a question of Dales and Lau. Finally we show that there exists a weight $\\omega$ on $\\mathbb{Z}$ such that the bidual of $\\ell^{\\, 1}(\\mathbb{Z}, \\omega)$ contains a radical element which is not nilpotent.", "revisions": [ { "version": "v1", "updated": "2017-08-31T09:32:40.000Z" } ], "analyses": { "subjects": [ "43A20", "46H10", "16N20" ], "keywords": [ "beurling algebra", "first arens product", "contains nilpotent elements", "results settles", "banach algebra" ], "note": { "typesetting": "TeX", "pages": 17, "language": "en", "license": "arXiv", "status": "editable" } } }