László, Lajos On a structured semidefinite program. (English) Zbl 1234.90010 Acta Univ. Sapientiae, Math. 3, No. 1, 77-89 (2011). Summary: The nonnegative biquadratics discussed comes from the Böttcher-Wenzel inequality. It is for some matrices a sum of squares of polynomials (SOS), in other cases not, depending on the nonzero pattern of the matrices at issue. Our aim was to draw a line between them. To prove the ‘not a SOS’ case we solve a semidefinite programming (SDP) problem. Subsequently a two-parameter version will be investigated. MSC: 90C22 Semidefinite programming 15A45 Miscellaneous inequalities involving matrices 65F15 Numerical computation of eigenvalues and eigenvectors of matrices Keywords:sum of squares; biquadratics PDFBibTeX XMLCite \textit{L. László}, Acta Univ. Sapientiae, Math. 3, No. 1, 77--89 (2011; Zbl 1234.90010)