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 , and a sequence , such that the entry of the matrix is the coefficient of the polynomial in the expansion of as a linear combination of the polynomials .
We consider this general framework. For a non-decreasing sequence we establish necessary and sufficient conditions on the sequence 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 和一个序列 ,这样 矩阵的项是多项式的系数 在扩展中 作为多项式的线性组合 。
我们考虑这个通用框架。对于非递减序列 我们在序列上建立了必要和充分的条件 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。