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Total non-negativity of some combinatorial matrices
Journal of Combinatorial Theory Series A ( IF 1.1 ) Pub Date : 2020-01-23 , DOI: 10.1016/j.jcta.2019.105179
David Galvin , Adrian Pacurar

Many combinatorial matrices — such as those of binomial coefficients, Stirling numbers of both kinds, and Lah numbers — are known to be totally non-negative, meaning that all minors (determinants of square submatrices) are non-negative.

The examples noted above can be placed in a common framework: for each one there is a non-decreasing sequence (a1,a2,), and a sequence (e1,e2,), such that the (m,k) entry of the matrix is the coefficient of the polynomial (xa1)(xak) in the expansion of (xe1)(xem) as a linear combination of the polynomials 1,xa1,,(xa1)(xam).

We consider this general framework. For a non-decreasing sequence (a1,a2,) we establish necessary and sufficient conditions on the sequence (e1,e2,) for the corresponding matrix to be totally non-negative. As corollaries we obtain total non-negativity of matrices of rook numbers of Ferrers boards, and of graph Stirling numbers of chordal graphs.



中文翻译:

某些组合矩阵的总非负性

已知许多组合矩阵(例如,二项式系数,两种斯特林数和Lah数)都是完全非负的,这意味着所有未成年人(平方子矩阵的行列式)都是非负的。

上面提到的示例可以放在一个公共框架中:每个框架都有一个不递减的序列 一种1个一种2和一个序列 Ë1个Ë2,这样 ķ 矩阵的项是多项式的系数 X-一种1个X-一种ķ 在扩展中 X-Ë1个X-Ë 作为多项式的线性组合 1个X-一种1个X-一种1个X-一种

我们考虑这个通用框架。对于非递减序列一种1个一种2 我们在序列上建立了必要和充分的条件 Ë1个Ë2相应的矩阵是完全非负的。作为推论,我们获得了Ferrers板的流向数矩阵和弦图的图斯特林数矩阵的总非负性。

更新日期:2020-01-23
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