BORROMEAN SURGERY AND THE CASSON INVARIANT

BORROMEAN SURGERY AND THE CASSON INVARIANT J.-B. MEILHANH Abstract. This note is based on a talk given at the conference Intelligence of low dimensionnal Topology, held in Osaka in November 2005. All results are taken from [M] (except for 2), where detailed proof can be found. 1. Motivations Let M be a closed oriented 3-manifold. A Borromean surgery move on M is defined as the surgery along a link L obtained by embedding in M a genus 3 handlebody H contain- ing a copy of the 6-component framed oriented link depicted below (we make use of the blackboard framing convention). 5 4 2 31 6 H We call L a Borromean surgery link. This notion was first introduced by S. Matveev [Mt] in slightly different terms. Matveev showed that two closed oriented 3-manifolds are Borromean equivalent, i.e. are related by a sequence of such surgery moves, if and only if they have the same homology and linking form. As a consequence, every oriented integral homology 3-sphere is obtained from S3 by surgery along claspers. It is thus a natural problem to give easily computable formulas for the variation of the Casson invariant ? under such a surgery move. Recall that two integral homology spheres are always related by a sequence of (±1)- framed surgeries along knots.

• component link


• borromean surgery link


• lescop's


• l1 ?


• borromean surgery


• trivalent vertices


• t145 ?