Document Type
Article
Department/Program
Mathematics
Journal Title
Special Matrices
Pub Date
2016
Volume
4
Issue
1
First Page
67
Abstract
A copositive matrix A is said to be exceptional if it is not the sum of a positive semidefinite matrix and a nonnegative matrix. We show that with certain assumptions on A(-1), especially on the diagonal entries, we can guarantee that a copositive matrix A is exceptional. We also show that the only 5-by-5 exceptional matrix with a hollow nonnegative inverse is the Horn matrix (up to positive diagonal congruence and permutation similarity).
Recommended Citation
Reams, Robert B. and Johnson, Charles R., Sufficient conditions to be exceptional (2016). Special Matrices, 4(1), 67-72.
10.1515/spma-2016-0007
DOI
10.1515/spma-2016-0007
COinS
