This paper expands on and refines some known and less well-known results about the finite subset spaces of a simplicial complex X including their connectivity and manifold structure. It also discusses the inclusion of the singletons into the three-fold subset space and shows that this subspace is weakly contractible but generally non-contractible unless X is a cogroup. Some homological calculations are provided.
Homology, Homotopy and Applications, Vol. 11 (2009), No. 2, pp.229-250.
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