{ "id": "1308.6105", "version": "v1", "published": "2013-08-28T09:27:01.000Z", "updated": "2013-08-28T09:27:01.000Z", "title": "On the algebraic unknotting number", "authors": [ "Maciej Borodzik", "Stefan Friedl" ], "comment": "32 pages, 18 figures", "categories": [ "math.GT" ], "abstract": "The algebraic unknotting number u_a(K) of a knot K was introduced by Hitoshi Murakami. It equals the minimal number of crossing changes needed to turn K into an Alexander polynomial one knot. In a previous paper the authors used the Blanchfield form of a knot K to define an invariant n(K) and proved that n(K) is a lower bound on u_a(K). They also showed that n(K) subsumes all previous classical lower bounds on the (algebraic) unknotting number. In this paper we prove that n(K)=u_a(K).", "revisions": [ { "version": "v1", "updated": "2013-08-28T09:27:01.000Z" } ], "analyses": { "keywords": [ "algebraic unknotting number", "hitoshi murakami", "classical lower bounds", "blanchfield form", "minimal number" ], "note": { "typesetting": "TeX", "pages": 32, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2013arXiv1308.6105B" } } }