The minimum rank problem: A counterexample

被引:12
|
作者
Kopparty, Swastik [2 ]
Rao, K. P. S. Bhaskara [1 ]
机构
[1] Indiana State Univ, Dept Math & Comp Sci, Terre Haute, IN 47809 USA
[2] MIT, Comp Sci & Artificial Intelligence Lab, Cambridge, MA 02139 USA
关键词
sign pattern matrix; zero nonzero pattern; minimum rank; minimum rank of a graph;
D O I
10.1016/j.laa.2007.10.016
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
We provide a counterexample to a recent conjecture that the minimum rank over the reals of every sign pattern matrix can be realized by a rational matrix. We use one of the equivalences of the conjecture and some results from projective geometry. As a consequence of the counterexample we show that there is a graph for which the minimum rank of the graph over the reals is strictly smaller than the minimum rank of the graph over the rationals. We also make some comments on the minimum rank of sign pattern matrices over different subfields of R. (C) 2007 Elsevier Inc. All rights reserved.
引用
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页码:1761 / 1765
页数:5
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