Local Lidskii's theorems for unitarily invariant norms

PEDRO GUSTAVO MASSEY; NOELIA BELÉN RIOS; DEMETRIO STOJANOFF

LINEAR ALGEBRA AND ITS APPLICATIONS

ELSEVIER SCIENCE INC

Lugar: Amsterdam; Año: 2018 vol. 557 p. 34 - 61

0024-3795

Lidskii´s additive inequalities (both for eigenvalues and singular values) can be interpretedas an explicit description of global minimizers of functions that are built on unitarily invariant norms, withdomains consisting of certain orbits of matrices (under the action of the unitary group). In this paper, we showthat Lidskii´s inequalities actually describe all global minimizers of such functions and that local minimizers are also global minimizers. We use these results to obtain partial results related to local minimizers of generalized frame operator distances in the context of finite frame theory.