【摘要】 目的　研究符号中心矩阵和 L矩阵 .方法　利用组合论和矩阵论方法 .结果和结论　给出极小符号中心矩阵的一个刻划定理及符号中心矩阵与 L 矩阵之间的关系 .同时也给出了元素全非零的符号中心矩阵和 L矩阵中负元个数的上界及其极矩阵的完全刻划更多还原

【Abstract】 Aim To study two classes of sign pattern matrices which are L matrices and sign central matrices. Methods By combinatorial and matrix theoretical methods. Results and Conclusion We first give a combinatorial characterization of minimal sign central matrices. Further, a relation of sign central matrices with L matrices be characterized. We also discuss the maximum number of negative entries in entrywise nonzero L matrices and sign central matrices.更多还原