ArticleOriginal scientific text

Title

On a property of weak resolvents and its application to a spectral problem

Authors 1

Affiliations

  1. Department of Mathematics and Computer Science, Adam Mickiewicz University, Matejki 48/49, 60-769 Poznań, Poland

Abstract

We show that the poles of a resolvent coincide with the poles of its weak resolvent up to their orders, for operators on Hilbert space which have some cyclic properties. Using this, we show that a theorem similar to the Mlak theorem holds under milder conditions, if a given operator and its adjoint have cyclic vectors.

Keywords

weak resolvent, cyclic vector, spectral radius, Hardy class, operator model theory, scattering theory, control theory

Bibliography

  1. H. R. Dowson, Spectral Theory of Linear Operators, Academic Press, London, 1978.
  2. N. Dunford and J. T. Schwartz, Linear Operators, Part I: General Theory, Intescience, New York, 1958.
  3. C. K. Fong, E. A. Nordgren, H. Radjavi and P. Rosenthal, Weak resolvents of linear operators, II, Indiana Univ. Math. J. 39 (1990), 67-83.
  4. J. W. Helton, Discrete time systems, operator models, and scattering theory, J. Funct. Anal. 16 (1974), 15-38.
  5. J. W. Helton, Systems with infinite-dimensional state space: the Hilbert space approach, Proc. IEEE 64 (1976), 145-160.
  6. P. Jakóbczak and J. Janas, On Nikolski theorem for several operators, Bull. Polish Acad. Sci. Math. 31 (1983), 369-374.
  7. J. Janas, On a theorem of Lebow and Mlak for several commuting operators, Studia Math. 76 (1983), 249-253.
  8. T. Kailath, Linear Systems, Prentice-Hall, Englewood Cliffs, N.J., 1980.
  9. R. E. Kalman, P. L. Falb and M. A. Arbib, Topics in Mathematical System Theory, McGraw-Hill, New York, 1969.
  10. T. Kato, Perturbation Theory for Linear Operators, 2nd ed., Springer, Berlin, 1976.
  11. P. D. Lax and R. S. Phillips, Scattering Theory, rev. ed., Academic Press, New York, 1989.
  12. A. Lebow, Spectral radius of an absolutely continuous operator, Proc. Amer. Math. Soc. 36 (1972), 511-514.
  13. W. Mlak, On a theorem of Lebow, Ann. Polon. Math. 35 (1977), 107-109.
  14. N. K. Nikol'skiĭ, A Tauberian theorem on the spectral radius, Sibirsk. Mat. Zh. 18 (1977), 1367-1372 (in Russian).
  15. E. Nordgren, H. Radjavi and P. Rosenthal, Weak resolvents of linear operators, Indiana Univ. Math. J. 36 (1987), 913-934.
  16. W. Rudin, Real and Complex Analysis, 2nd ed., McGraw-Hill, New York, 1974.
  17. B. Sz.-Nagy and C. Foiaş, Harmonic Analysis of Operators on Hilbert Space, North-Holland, Amsterdam, 1970.
Pages:
263-268
Main language of publication
English
Received
1995-11-29
Published
1997
Exact and natural sciences