2005/09/21 by Richard M. Timoney, Timoney, Richard M. · 1 citation
Computer Science · Mathematics · #46L07 #47B47 #Advanced Operator Algebra Research #FOS: Mathematics #Matrix Theory and Algorithms #Operator Algebras (math.OA) #Spectral Theory in Mathematical Physics #math.OA #msc:46L07 #msc:47B47
paper · pdf · doi:10.48550/arxiv.math/0509491
27 pages, J. Operator Theory (to appear)
arxiv created 2005/09/21 · openalex publication_date 2005/09/21 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a formula for the norm of an elementary operator on a C*-algebra that seems to be new. The formula involves (matrix) numerical ranges and a kind of geometrical mean for positive matrices, the tracial geometric mean, which seems not to have been studied previously and has interesting properties. In addition, we characterise compactness of elementary operators.