Seminário Análise Funcional e Aplicações 

11/01/2008, 15:00 — 16:00 — Sala P3.10, Pavilhão de Matemática
Ilya Spitkovsky, College of William and Mary, Williamsburg, Virginia, USA

Spectral dominance and commuting chains

Positive semi-definite (PSD) operator "spectrally dominates" PSD operator if is PSD for all . We (i) give a new characterization of spectral dominance in finite dimensions in terms of a monotonic chain of intermediate, pairwise commuting operators and (ii) determine for which pairs spectral dominance persists under the taking of arbitrary compressions. Earlier results about spectral dominance are proven (in finite dimensions) in new ways, and several corollary observations are made. This is a joint work with Charlie Johnson and Bich Hoai, accepted for publication by Proceedings of the AMS (and is accessible for students).