The Topology of the External Activity Complex of a Matroid

[摘要] We prove that the external activity complex $\textrm{Act}_<(M)$ of a matroid is shellable. In fact, we show that every linear extension of LasVergnas's external/internal order $<_{ext/int}$ on $M$ provides a shelling of $\textrm{Act}_<(M)$. We al

[学科分类] 离散数学和组合数学

[关键词] Matroid theory;Shellability;Linear extensions