{ "id": "1701.01711", "version": "v1", "published": "2017-01-06T18:00:40.000Z", "updated": "2017-01-06T18:00:40.000Z", "title": "Functions on surfaces and constructions of manifolds in dimensions three, four and five", "authors": [ "David T Gay" ], "comment": "19 pages, 5 figures", "categories": [ "math.GT" ], "abstract": "We offer a new proof that two closed oriented 4-manifolds are cobordant if their signatures agree, in the spirit of Lickorish's proof that all closed oriented 3-manifolds bound 4-manifolds. Where Lickorish uses Heegaard splittings we use trisections. In fact we begin with a subtle recasting of Lickorish's argument: Instead of factoring the gluing map for a Heegaard splitting as a product of Dehn twists, we encode each handlebody in a Heegaard splitting in terms of a Morse function on the surface and build the 4-manifold from a generic homotopy between the two functions. This extends up a dimension by encoding a trisection of a closed 4-manifold as a triangle (circle) of functions and constructing an associated 5-manifold from an extension to a 2-simplex (disk) of functions. This borrows ideas from Hatcher and Thurston's proof that the mapping class group of a surface is finitely presented.", "revisions": [ { "version": "v1", "updated": "2017-01-06T18:00:40.000Z" } ], "analyses": { "subjects": [ "57M99", "57R90", "57R45" ], "keywords": [ "constructions", "heegaard splitting", "dehn twists", "lickorishs proof", "lickorishs argument" ], "note": { "typesetting": "TeX", "pages": 19, "language": "en", "license": "arXiv", "status": "editable" } } }