论文标题
弹性元素的分离器定理,$ 3 $连接的Matroids
A splitter theorem for elastic elements in $3$-connected matroids
论文作者
论文摘要
如果$ {\ rm si}(m/e)$,$ 3 $连接的Matroid $ m $的元素$ e $是弹性的,简化了$ m/e $,以及$ {\ rm co}(m \ rm co}(m \ backslash e)$,$ m \ m \ backslash e $ cosimplification of $ m \ backslash e $,是$ 3 $ -bacnect。最近显示的是,如果$ | e(m)| \ geq 4 $,那么$ m $至少有四个弹性元素,因为$ m $没有$ 4 $ element粉丝,也没有特定家族的$ 3 $ separators的成员。在本文中,我们将此车轮和旋转类型的结果扩展到了分离器定理,在该定理中,删除元素是关于弹性的,并保留指定的$ 3 $连接的未成年人。我们还证明,如果$ m $具有四个弹性元素,那么它具有三个路径宽度。最后,我们解决了一个惠特尔和威廉姆斯的问题,并表明过去的类似结果(去除元素相对于固定基础)是这项工作的后果。
An element $e$ of a $3$-connected matroid $M$ is elastic if ${\rm si}(M/e)$, the simplification of $M/e$, and ${\rm co}(M\backslash e)$, the cosimplification of $M\backslash e$, are both $3$-connected. It was recently shown that if $|E(M)|\geq 4$, then $M$ has at least four elastic elements provided $M$ has no $4$-element fans and no member of a specific family of $3$-separators. In this paper, we extend this wheels-and-whirls type result to a splitter theorem, where the removal of elements is with respect to elasticity and keeping a specified $3$-connected minor. We also prove that if $M$ has exactly four elastic elements, then it has path-width three. Lastly, we resolve a question of Whittle and Williams, and show that past analogous results, where the removal of elements is relative to a fixed basis, are consequences of this work.