44 research outputs found
Almost invariant half-spaces for operators on Hilbert space. II: operator matrices
This paper is a sequel to [6]. In that paper we transferred the discussions
in [1] and [13] concerning almost invariant half-spaces for operators on
complex Banach spaces to the context of operators on Hilbert space, and we gave
easier proofs of the main results in [1] and [13]. In the present paper we
discuss consequences of the above-mentioned results for the matricial structure
of operators on Hilbert space
Almost commuting matrices
It is shown that if A and B are n x n complex matrices with A = A* and ||AB - BA||2/(n - 1), then there exist n x n matrices A' and B' with A' = A'* such that A'B' = B'A' and ||A - A'||[les] [epsilon], ||B - B'||[les] [epsilon].Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23719/1/0000691.pd
El problema de los subespacios invariantes
El Prof. Carl Pearcy, de la Universidad de Michigan en Ann Arbor, visitĂł la Escuela de Matemática en noviembre de 1983, y ofreciĂł un minicurso de tres sesiones sobre el problema de los subespacios invariantes. Dicho problema pide averiguar si un operador acotado sobre un espacio de Banach posee un subespacio cerrado no trivial invariante. El Dr. Pearcy era un experto en esta rama del análisis funcional. Estas notas del minicurso, tomados por Joseph Várilly, circularon como manuscrito mecanografiado durante varios años.UCR::VicerrectorĂa de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Matemátic
Dilation theory and systems of simultaneous equations in the predual of an operator algebra. II
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46272/1/209_2005_Article_BF01163170.pd