Completely positive matrices of order
with
-graph
Abstract
We characterize completely positive matrices of order five whose associated graph is a
-graph not completely positive, unifying and improving results obtained by Xu. We show by counterexamples that two characterizations obtained by Xu are incorrect
![\widehat{CP}](http://212.189.136.205/plugins/generic/latexRender/cache/7da99fd6b83b0348e5b1e02d9f9a470a.png)
Keywords:
doubly non-negative matrices; completely positive matrices; $\widehat{CP}$-graphs
Full Text: PDF