Vol. 91, No. 2, 1980

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Commuting hyponormal operators

James Guyker

Vol. 91 (1980), No. 2, 307–325
Abstract

A hyponormal operator is normal if it commutes with a contraction T of a Hilbert space, whose powers go to zero strongly, such that 1 TT has finite-dimensional range and the coefficients of the characteristic function of T lie in a commutative C-algebra. The hyponormal operator is a constant multiple of the identity transformation if the rank of 1 TT is one.

Mathematical Subject Classification 2000
Primary: 47B20
Secondary: 47A56
Milestones
Received: 5 June 1979
Revised: 21 February 1980
Published: 1 December 1980
Authors
James Guyker