全部 标题 作者
关键词 摘要

OALib Journal期刊
ISSN: 2333-9721
费用:99美元

查看量下载量

相关文章

更多...
Mathematics  2011 

A counterexample to conjecture 18.5 in "Geometric Etudes in Combinatorial Mathematics", second edition

Full-Text   Cite this paper   Add to My Lib

Abstract:

A collection of sets $\Fscr$ has the $(p,q)$-property if out of every $p$ elements of $\Fscr$ there are $q$ that have a point in common. A transversal of a collection of sets $\Fscr$ is a set $A$ that intersects every member of $\Fscr$. Gr\"unbaum conjectured that every family $\Fscr$ of closed, convex sets in the plane with the $(4,3)$-property and at least two elements that are compact has a transversal of bounded cardinality. Here we construct a counterexample to his conjecture. On the positive side, we also show that if such a collection $\Fscr$ contains two {\em disjoint} compacta then there is a transveral of cardinality at most 13.

Full-Text

Contact Us

service@oalib.com

QQ:3279437679

WhatsApp +8615387084133