Löwner's Operator and Spectral Functions in Euclidean Jordan Algebras
Defeng Sun,
Jie Sun
Department of Mathematics, National University of Singapore, Singapore 119077
Department of Decision Sciences, National University of Singapore, Singapore 119077
matsundf{at}nus.edu.sg
bizsunj{at}nus.edu.sg
We study analyticity, differentiability, and semismoothness of Löwner's operator and spectral functions under the framework of Euclidean Jordan algebras. In particular, we show that many optimization-related classical results in the symmetric matrix space can be generalized within this framework. For example, the metric projection operator over any symmetric cone defined in a Euclidean Jordan algebra is shown to be strongly semismooth. The research also raises several open questions, whose answers would be of strong interest for optimization research.
Key Words: Euclidean Jordan algebras; Löwner's operator; spectral functions; semismoothness
History: Received: December 28, 2004;
revision received: July 5, 2007;
Copyright © 2008 by INFORMS.