Hostname: page-component-7479d7b7d-c9gpj Total loading time: 0 Render date: 2024-07-13T15:55:31.369Z Has data issue: false hasContentIssue false

Sums and Products of Weighted Shifts

Published online by Cambridge University Press:  20 November 2018

Laurent W. Marcoux*
Affiliation:
Department of Mathematical Sciences University of Alberta Edmonton, Alberta T6G 2G1, email: L.Marcoux@ualberta.ca
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

In this article it is shown that every bounded linear operator on a complex, infinite dimensional, separable Hilbert space is a sum of at most eighteen unilateral (alternatively, bilateral) weighted shifts. As well, we classify products of weighted shifts, as well as sums and limits of the resulting operators.

Keywords

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 2001

References

[1] Ballantine, C. S., Products of positive definite matrices IV. Linear Algebra Appl. 3 (1970), 79114.Google Scholar
[2] Berg, I. D., An extension of the Weyl-von Neumann theorem to normal operators. Trans. Amer.Math. Soc. 160 (1971), 365371.Google Scholar
[3] Berg, I. D., Index theory for perturbations of direct sums of normal operators and weighted shifts. Canad. J. Math. 30 (1978), 11521165.Google Scholar
[4] Brown, A. and Halmos, P. R., Algebraic properties of Toeplitz operators. J. Reine Angew. Math. 213(1963/1964), 89–102.Google Scholar
[5] Brown, L. G., Almost every proper isometry is a shift. Indiana Univ. Math. J. 23 (1973), 429431.Google Scholar
[6] Davidson, K. R., C*-algebras by example. Fields Institute Monographs 6, Amer.Math. Soc., Providence, RI, 1996.Google Scholar
[7] Ding, X. H. and Shi, G., Products of weighted shift operators. J. Math. Res. Exposition 15 (1995), 471472.Google Scholar
[8] Douglas, R. G., Banach algebra techniques in operator theory. Academic Press, New York, 1972.Google Scholar
[9] Fillmore, P. A., On sums of projections. J. Funct. Anal. 4 (1969), 146152.Google Scholar
[10] Fong, C. K.,Miers, C. R. and Sourour, A. R., Lie and Jordan ideals of operators on Hilbert space. Proc. Amer. Math. Soc. 84 (1982), 516520.Google Scholar
[11] Fong, C. K. and Sourour, A. R., Sums and products of quasinilpotent operators. Proc. Roy. Soc. Edinburgh Sect. A 99 (1984), 193200.Google Scholar
[12] Fong, C. K. and Wu, P. Y., Diagonal operators: dilation, sum and product. Acta Sci.Math. (Szeged) 57 (1993), 125138.Google Scholar
[13] Hadwin, D. H., Limits of products of positive operators. Bull. London Math. Soc. 27 (1995), 479482.Google Scholar
[14] Halmos, P. R., Products of shifts. Duke Math. J. 39 (1972), 779787.Google Scholar
[15] Halmos, P. R., Limits of shifts. Acta Sci.Math. 34 (1973), 131139.Google Scholar
[16] Herrero, D. A., Quasidiagonality, similarity and approximation by nilpotent operators. Indiana Univ. Math. J. 30 (1981), 549571.Google Scholar
[17] Herrero, D. A., Unitary orbits of power partial isometries and approximation by block-diagonal nilpotents. Topics in modern operator theory, Advances and Applications 2, Birkhäuser-Verlag, pages 171210, 1981.Google Scholar
[18] Herrero, D. A., An essay on quasitriangularity. Advances and Applications, Birkhäuser-Verlag 28, 1988, 125154.Google Scholar
[19] Khalkhali, M., Laurie, C., Mathes, B. and Radjavi, H., Approximation by products of positive operators. J. Operator Theory 29 (1993), 237247.Google Scholar
[20] Murphy, G. J., Diagonalising operators on Hilbert space. Proc. Roy. Irish Acad. Sect. A 87 (1987), 6771.Google Scholar
[21] Pearcy, C. and Salinas, N., Compact perturbations of seminormal operators. Indiana Univ.Math. J. 22 (1973), 789793.Google Scholar
[22] Radjavi, H., On self-adjoint factorization of operators. Canad. J. Math. 21 (1969), 14211426.Google Scholar
[23] Radjavi, H., Products of hermitian matrices and symmetries. Proc. Amer.Math. Soc. 21 (1969), 369372.Google Scholar
[24] Radjavi, H., Products of hermitian matrices and symmetries; errata. Proc. Amer. Math. Soc. 26(1970), 701.Google Scholar
[25] Salinas, N., Reducing essential eigenvalues. DukeMath. J. 40 (1973), 561580.Google Scholar
[26] Shields, A. L., Weighted shift operators and analytic function theory. Math. Surveys 13, Amer.Math. Soc., Providence, RI, 1974, 49–128.Google Scholar
[27] Sikonia, W., The von Neumann converse of Weyl's theorem. Indiana Univ.Math. J. 21 (1971), 121123.Google Scholar
[28] Voiculescu, D., A non-commutative Weyl-von Neumann theorem. Rev. Roumaine Math. Pures Appl. 21 (1976), 97113.Google Scholar
[29] Wu, P. Y., Products of nilpotent matrices. Linear Algebra Appl. 96 (1987), 227232.Google Scholar
[30] Wu, P. Y., Products of normal operators. Canad. J. Math 40 (1988), 13221330.Google Scholar
[31] Wu, P. Y., The operator factorization problems. Linear Algebra Appl. 117 (1989), 3563.Google Scholar
[32] Wu, P. Y., Additive combinations of special operators. Functional analysis and operator theory 30, Warsaw, 1992, Banach Center Publ., Polish Acad. Sci., Warsaw, 1994, 377–361.Google Scholar