Some combinatorial properties of flag simplicial pseudomanifolds and spheres
نویسنده
چکیده
A simplicial complex ∆ is called flag if all minimal nonfaces of ∆ have at most two elements. The following are proved: First, if ∆ is a flag simplicial pseudomanifold of dimension d− 1, then the graph of ∆ (i) is (2d−2)-vertex-connected and (ii) has a subgraph which is a subdivision of the graph of the d-dimensional cross-polytope. Second, the h-vector of a flag simplicial homology sphere ∆ of dimension d−1 is minimized when ∆ is the boundary complex of the d-dimensional
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