{ "id": "1703.09549", "version": "v1", "published": "2017-03-28T12:42:53.000Z", "updated": "2017-03-28T12:42:53.000Z", "title": "Variations on the sum-product problem II", "authors": [ "Brendan Murphy", "Oliver Roche-Newton", "Ilya Shkredov" ], "comment": "This paper supercedes arXiv:1603.06827", "categories": [ "math.CO", "math.NT" ], "abstract": "This is a sequel to the paper arXiv:1312.6438 by the same authors. In this sequel, we quantitatively improve several of the main results of arXiv:1312.6438, as well as generalising a method therein to give a near-optimal bound for a new expander. The main new results are the following bounds, which hold for any finite set $A \\subset \\mathbb R$: \\begin{align*} \\exists a \\in A \\text{ such that }|A(A+a)| &\\gtrsim |A|^{\\frac{3}{2}+\\frac{1}{186}}, |A(A-A)| &\\gtrsim |A|^{\\frac{3}{2}+\\frac{1}{34}}, |A(A+A)| &\\gtrsim |A|^{\\frac{3}{2}+\\frac{5}{242}}, |\\{(a_1+a_2+a_3+a_4)^2+\\log a_5 : a_i \\in A \\}| &\\gg \\frac{|A|^2}{\\log |A|}. \\end{align*}", "revisions": [ { "version": "v1", "updated": "2017-03-28T12:42:53.000Z" } ], "analyses": { "keywords": [ "sum-product problem", "variations", "finite set", "main results" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }