2010/09/06 by Greene, Joshua Evan · 1 citation
#FOS: Mathematics #Geometric Topology (math.GT)
paper · doi:10.48550/arxiv.1009.1130
We prove that if positive integer p-surgery along a knot K ⊂ S3 produces an L-space and it bounds a sharp 4-manifold, then the knot genus obeys the bound 2g(K) -1 ≤ p - √(3p+1). Moreover, there exists an infinite family of pairs (Kn,pn) attaining this bound, where Kn denotes an n-fold iterated cable of the unknot and pn → ∞. In particular, the stated bound applies when the knot surgery produces a lens space or a connected sum thereof. Combined with work of Gordon-Luecke, Hoffman, and Matignon-Sayari, it follows that if surgery along a knot produces a connected sum of lens spaces, then the knot is either a torus knot or a cable thereof, confirming the cabling conjecture in this case.