Titlebook: Contributions to Operator Theory and its Applications; Proceedings of the C I. Gohberg,J. W. Helton,L. Rodman Conference proceedings 1988 B

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抚慰

繁荣地区

Block Toeplitz Operators with Rational Symbols,tion to singular systems with boundary conditions. The case of finite block Toeplitz matrices is also included. Fredholm characteristics are computed. All formulas are explicit and based on a realization of the symbol as a transfer function of a singular system.

享乐主义者

Conditional Expectations and Invariant Subspaces,and let M be a subspaçe of H. A sufficient condition for M to be invariant for Ф (А.)•A is obtained. A generalization involving sequences of conditional expectations yields a simplified and conceptually different proof of a recent theorem about operator factorization with respect to commutative sets

Neuralgia

Affection

Analytic Functions of Elements of the Calkin Algebra, and Their Limits,ator on the Hubert space ., and σ.(A) ⊂Λ} is described in terms of f, Λ and the different parts of the spectra of the operators. (Here à denotes the canonical projection of A in the Calkin algebra, and σ.(A) is the essential spectrum of A.) The results include spectral characterizations of interior

小故事

,2 — Chordal Graphs,∉ E where e. is the standard orthonormal basis of ℂ.. M. (ℂ). is the set of positive semi-definite n × n matrices with complex entries. For X . M. (ℂ). a cone, define the order of X, denoted ord(X), to be the smallest integer k such that the elements of X of rank at most k generate X as a cone. For

dominant

End Point Results for Estimates of Singular Values of Singular Integral Operators,n between the smoothness of b(x) (measured using the Besov scale) and the decay of the singular values of the commutator (measured using the Schatten ideals) is well understood when the index, p, is greater than one. Here we offer results for the case p = 1. The simplest example, when the integral o

染色体

Shift Invariant Subspaces, Passivity, Reproducing Kernels and ,,-Optimization,ircle. These notions, as well as how they are related to each other, are analyzed from several points of view: energy bookkeeping in the circuit, analytic conditions on . and on the associated scattering matrix ., geometry of shift invariant subspaces, positive definiteness conditions on associated

陶醉

Toeplitz Operators on Multiply Connected Domains and Theta Functions,ed by M.B. Abrahamse is refined. This is accomplished by viewing the planar domain as a domain on its double and applying the methods of Hilbert barrier problems associated with divisors as developed by R.N. Abdulaev, N. Koppelman, Yu.L. Rodin and E.I. Zverovich. In essence the results on barrier pr