Unknotting information from Heegaard Floer homology
Geometric Topology
2007-05-23 v1
Abstract
We use Heegaard Floer homology to obtain bounds on unknotting numbers. This is a generalisation of Ozsvath and Szabo's obstruction to unknotting number one. We determine the unknotting numbers of 9_10, 9_13, 9_35, 9_38, 10_53, 10_101 and 10_120; this completes the table of unknotting numbers for prime knots with crossing number nine or less. Our obstruction uses a refined version of Montesinos' theorem which gives a Dehn surgery description of the branched double cover of a knot.
Keywords
Cite
@article{arxiv.math/0506485,
title = {Unknotting information from Heegaard Floer homology},
author = {Brendan Owens},
journal= {arXiv preprint arXiv:math/0506485},
year = {2007}
}
Comments
26 pages, 13 figures (xypic)