On Polytopes that are Simple at the Edges

Research paper by V. A. Timorin

Indexed on: 01 Jul '01Published on: 01 Jul '01Published in: Functional Analysis and Its Applications


We study some combinatorial properties of polytopes that are simple at the edges. We give an elementary geometric proof of an analog of the hard Lefschetz theorem for the polytopes for which the distance between any two nonsimple vertices is sufficiently large. This implies that the h-vector of such polytopes satisfies the relations \(h_{\left[ {{d \mathord{\left/ {\vphantom {d 2}} \right. \kern-\nulldelimiterspace} 2}} \right]} \geqslant h_{\left[ {{d \mathord{\left/ {\vphantom {d 2}} \right. \kern-\nulldelimiterspace} 2}} \right] + 1} \geqslant \cdot \cdot \cdot \geqslant h_d = 1\), where d is the dimension of the polytope, which proves a special case of Stanley's conjecture.