{ "id": "0910.2872", "version": "v1", "published": "2009-10-15T13:33:28.000Z", "updated": "2009-10-15T13:33:28.000Z", "title": "The Goeritz matrix and signature of a two bridge knot", "authors": [ "Michael Gallaspy", "Stanislav Jabuka" ], "comment": "22 pages, 8 figures", "categories": [ "math.GT" ], "abstract": "According to a formula by Gordon and Litherland, the signature of a knot K can be computed as the signature of a Goeritz matrix of K minus a suitable correction term, read off from the diagram of K. In this article, we consider the family of two bridge knots K(p/q) and compute the signature of their Goeritz matrices in terms of the coefficients of the continued fraction expansion of p/q. In many cases we also compute the value of the correction term. We show that for every two bridge knot K(p/q), there are \"even continued fraction expansions\" of p/q, for which the correction term vanishes, thereby fully computing the signature of K(p/q). We provide an algorithm for finding even continued fraction expansions. This article is the result of an REU study conducted by the first author under the direction of the second.", "revisions": [ { "version": "v1", "updated": "2009-10-15T13:33:28.000Z" } ], "analyses": { "subjects": [ "57M25", "57N70" ], "keywords": [ "bridge knot", "goeritz matrix", "continued fraction expansion", "correction term vanishes", "suitable correction term" ], "note": { "typesetting": "TeX", "pages": 22, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2009arXiv0910.2872G" } } }