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Oct 21, 2019 at 20:50 comment added Hans @IanAgol Thank you very much. Both the comments and references are very helpful.
Oct 18, 2019 at 9:27 comment added Ian Agol For separable subgroups of the mapping class group, check out: arxiv.org/abs/math/0505225
Oct 18, 2019 at 9:18 comment added Ian Agol The paper sciencedirect.com/science/article/pii/0040938389900116 gives some relation between the Casson invariant and the mapping class group of Heegaard splittings. In particular, there is a certain subgroup of the mapping class group for which modifying a Heegaard splitting by an element of this group does not change the Casson invariant (see Proposition 3.5 of this paper for a more precise statement).
Oct 16, 2019 at 17:48 comment added Ian Agol The gluing map is only well defined up to double cosets by the handlebody groups (subgroups extending over a chosen handlebody). So there’s not a close relation between the gluing maps and the topology. Nevertheless, see: arxiv.org/abs/1312.2293
Oct 16, 2019 at 3:51 comment added Ryan Budney @MarkSapir: that's true for surface bundles (genus 2 or higher) over the circle, with the homeomorphism being the bundle monodromy.
Oct 16, 2019 at 0:36 comment added Andy Putman @MarkSapir: Sadly, that's not true. The issue is that there are many pseudo-Anosov mapping classes that extend over the handlebody. A Heegaard splitting using one of these will yield the 3-sphere.
Oct 16, 2019 at 0:15 review First posts
Oct 16, 2019 at 1:06
Oct 16, 2019 at 0:14 comment added user6976 If the homomorphism is pseudo-Anosov, then the manifold is hyperbolic?
Oct 16, 2019 at 0:10 history asked Hans CC BY-SA 4.0