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Excluded minors are almost fragile II: Essential elements
Journal of Combinatorial Theory Series B ( IF 1.4 ) Pub Date : 2023-09-04 , DOI: 10.1016/j.jctb.2023.08.004
Nick Brettell , James Oxley , Charles Semple , Geoff Whittle

Let M be an excluded minor for the class of P-representable matroids for some partial field P, let N be a 3-connected strong P-stabilizer that is non-binary, and suppose M has a pair of elements {a,b} such that Ma,b is 3-connected with an N-minor. Suppose also that |E(M)||E(N)|+11 and Ma,b is not N-fragile. In the prequel to this paper, we proved that Ma,b is at most five elements away from an N-fragile minor. An element e in a matroid M is N-essential if neither M/e nor Me has an N-minor. In this paper, we prove that, under mild assumptions, Ma,b is one element away from a minor having at least r(M)2 elements that are N-essential.



中文翻译:

被排除在外的未成年人几乎是脆弱的二:基本要素

M为该类别的排除未成年人- 某些部分场的可表示拟阵,令N为 3 连通强-非二元稳定器,假设M有一对元素{A,}这样中号A,是 3 与N小调相连。还假设|中号|||+11中号A,不是N-脆弱的。在本文的前传中,我们证明了中号A,N脆弱小数最多五个元素。拟阵中的元素e中号N-必需的,如果两者都不是中号/e也不中号eN小调。在本文中,我们证明,在温和的假设下,中号A,距离未成年人至少有一个元素r中号-2N必需的元素。

更新日期:2023-09-05
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