{ "id": "1808.06665", "version": "v1", "published": "2018-08-20T19:30:08.000Z", "updated": "2018-08-20T19:30:08.000Z", "title": "Cayley Digraphs Associated to Arithmetic Groups", "authors": [ "David Covert", "Yeşim Demiroğlu Karabulut", "Jonathan Pakianathan" ], "categories": [ "math.CO", "math.NT" ], "abstract": "We explore a paradigm which ties together seemingly disparate areas in number theory, additive combinatorics, and geometric combinatorics including the classical Waring problem, the Furstenberg-S\\'{a}rk\\\"{o}zy theorem on squares in sets of integers with positive density, and the study of triangles (also called $2$-simplices) in finite fields. Among other results we show that if $\\mathbb{F}_q$ is the finite field of odd order $q$, then every matrix in $Mat_d(\\mathbb{F}_q), d \\geq 2$ is the sum of a certain (finite) number of orthogonal matrices, this number depending only on $d$, the size of the matrix, and on whether $q$ is congruent to $1$ or $3$ (mod $4$), but independent of $q$ otherwise.", "revisions": [ { "version": "v1", "updated": "2018-08-20T19:30:08.000Z" } ], "analyses": { "keywords": [ "arithmetic groups", "cayley digraphs", "finite field", "geometric combinatorics", "orthogonal matrices" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }