{ "id": "1810.03680", "version": "v1", "published": "2018-10-08T20:00:04.000Z", "updated": "2018-10-08T20:00:04.000Z", "title": "Binary Quadratic Forms in Difference Sets", "authors": [ "Alex Rice" ], "comment": "14 pages", "categories": [ "math.NT", "math.CA", "math.CO" ], "abstract": "We show that if $h(x,y)=ax^2+bxy+cy^2\\in \\mathbb{Z}[x,y]$ satisfies $b^2\\neq 4ac$, then any subset of $\\{1,2,\\dots,N\\}$ with no nonzero differences in the image of $h$ has size at most a constant depending on $h$ times $N\\exp(-c\\sqrt{\\log N})$, where $c=c(h)>0$. We achieve this goal by adapting an $L^2$ density increment strategy previously used to establish analogous results for sums of one or more single-variable polynomials. Our exposition is thorough and self-contained, in order to serve as an accessible gateway for readers who are unfamiliar with previous implementations of these techniques.", "revisions": [ { "version": "v1", "updated": "2018-10-08T20:00:04.000Z" } ], "analyses": { "keywords": [ "binary quadratic forms", "difference sets", "density increment strategy", "nonzero differences", "establish analogous results" ], "note": { "typesetting": "TeX", "pages": 14, "language": "en", "license": "arXiv", "status": "editable" } } }