Positive univariate trace polynomials
Rings and Algebras
2021-06-03 v2 Operator Algebras
Abstract
A univariate trace polynomial is a polynomial in a variable x and formal trace symbols Tr(x^j). Such an expression can be naturally evaluated on matrices, where the trace symbols are evaluated as normalized traces. This paper addresses global and constrained positivity of univariate trace polynomials on symmetric matrices of all finite sizes. A tracial analog of Artin's solution to Hilbert's 17th problem is given: a positive semidefinite univariate trace polynomial is a quotient of sums of products of squares and traces of squares of trace polynomials.
Cite
@article{arxiv.2009.10081,
title = {Positive univariate trace polynomials},
author = {Igor Klep and James Eldred Pascoe and Jurij Volčič},
journal= {arXiv preprint arXiv:2009.10081},
year = {2021}
}