{ "id": "0708.2304", "version": "v2", "published": "2007-08-17T01:15:26.000Z", "updated": "2007-08-21T14:57:58.000Z", "title": "Inverse problems for linear forms over finite sets of integers", "authors": [ "Melvyn B. Nathanson" ], "comment": "12 pages; minor corrections", "categories": [ "math.NT", "math.CO" ], "abstract": "Let f(x_1,x_2,...,x_m) = u_1x_1+u_2 x_2+... + u_mx_m be a linear form with positive integer coefficients, and let N_f(k) = min{|f(A)| : A \\subseteq Z and |A|=k}. A minimizing k-set for f is a set A such that |A|=k and |f(A)| = N_f(k). A finite sequence (u_1, u_2,...,u_m) of positive integers is called complete if {\\sum_{j\\in J} u_j : J \\subseteq {1,2,..,m}} = {0,1,2,..., U}, where $U = \\sum_{j=1}^m u_j.$ It is proved that if f is an m-ary linear form whose coefficient sequence (u_1,...,u_m) is complete, then N_f(k) = Uk-U+1 and the minimizing k-sets are precisely the arithmetic progressions of length k. Other extremal results on linear forms over finite sets of integers are obtained.", "revisions": [ { "version": "v2", "updated": "2007-08-21T14:57:58.000Z" } ], "analyses": { "subjects": [ "11P70", "11B25", "11B37", "11B75", "11A25" ], "keywords": [ "finite sets", "inverse problems", "minimizing k-set", "m-ary linear form", "finite sequence" ], "note": { "typesetting": "TeX", "pages": 12, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2007arXiv0708.2304N" } } }