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Surgery triangles are an important computational tool in Floer homology. Given a connected oriented surface $Sigma$, we consider the abelian group $K(Sigma)$ generated by bordered 3-manifolds with boundary $Sigma$, modulo the relation that the three manifolds involved in any surgery triangle sum to zero. We show that $K(Sigma)$ is a finitely generated free abelian group and compute its rank. We also construct an explicit basis and show that it generates all bordered 3-manifolds in a certain stronger sense. Our basis is strictly contained in another finite generating set which was constructed previously by Baldwin and Bloom. As a byproduct we confirm a conjecture of Blokhuis and Brouwer on spanning sets for the binary symplectic dual polar space.
For every $k geq 2$ we construct infinitely many $4k$-dimensional manifolds that are all stably diffeomorphic but pairwise not homotopy equivalent. Each of these manifolds has hyperbolic intersection form and is stably parallelisable. In fact we cons
It is shown that any closed three-manifold M obtained by integral surgery on a knot in the three-sphere can always be constructed from integral surgeries on a 3-component link L with each component being an unknot in the three-sphere. It is also inte
Two triples of triangles having pairwise disjoint outlines in 3-space are called combinatorially isotopic if one triple can be obtained from the other by a continuous motion during which the outlines of the triangles remain pairwise disjoint. We conj
We classify those compact 3-manifolds with incompressible toral boundary whose fundamental groups are residually free. For example, if such a manifold $M$ is prime and orientable and the fundamental group of $M$ is non-trivial then $M cong Sigmatimes S^1$, where $Sigma$ is a surface.
In this paper we explore the topological properties of self-replicating, 3-dimensional manifolds, which are modeled by idempotents in the (2+1)-cobordism category. We give a classification theorem for all such idempotents. Additionally, we characteri