arXiv subjects
Publications and source records attributed to Imre Bokor.
The classical Kneser-Milnor theorem says that every closed oriented connected 3-dimensional manifold admits a unique connected sum decomposition into manifolds that cannot be decomposed any further. We discuss to what degree such decompositions exist in higher dimensions and we show that in many settings uniqueness fails in higher dimensions.
Baues and Bleille showed that, up to oriented homotopy equivalence, a Poincare duality complex of dimension $n \ge 3$ with $(n-2)$-connected universal cover, is classified by its fundamental group, orientation class and the image of its fundamental class in the homology of the fundamental group. We generalise Turaev's results for the case $n=3$, by providing necessary and sufficient conditions for a triple $(G, ω, μ)$, comprising a group, $G$, $ω\in H^{1}(G;\mathbb{Z}/2\mathbb{Z})$ and $μ\in H_{3}(G, \mathbb{Z}^ω)$ to be realised by a Poincaré duality complex of dimension $n$ with $(n-2)$-connected universal cover, and by showing that such a complex is a connected sum of two such complexes if and only if its fundamental group is a free product of groups.