{ "id": "1409.3869", "version": "v1", "published": "2014-09-12T21:28:19.000Z", "updated": "2014-09-12T21:28:19.000Z", "title": "Selections Without Adjacency on a Rectangular Grid", "authors": [ "Jacob A. Siehler" ], "categories": [ "math.CO" ], "abstract": "Using T(m,n;k) to denote the number of ways to make a selection of k squares from an (m x n) rectangular grid with no two squares in the selection adjacent, we give a formula for T(2,n;k), prove some identities satisfied by these numbers, and show that T(2,n;k) is given by a degree k polynomial in n. We give simple formulas for the first few (most significant) coefficients of the polynomials. We give corresponding results for T(3,n;k) as well. Finally we prove a unimodality theorem which shows, in particular, how to choose k in order to maximize T(2,n;k).", "revisions": [ { "version": "v1", "updated": "2014-09-12T21:28:19.000Z" } ], "analyses": { "subjects": [ "05A15" ], "keywords": [ "rectangular grid", "polynomial", "selection adjacent", "simple formulas", "unimodality theorem" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2014arXiv1409.3869S" } } }