Weak semicontinuity for unbounded operators

  • Kim, Hyoungsoon (Department of Mathematics, Yonsei University, Kangwondo 220-710)
  • Published : 1997.08.01

Abstract

Let A be a $C^*$-algebra and $A^**$ its enveloping von Neumann algebra. Pedersen and Akemann developed four concepts of lower semicontinuity for elements of $A^**$. Later, Brown suggested using only three classes: strongly lsc, middle lsc, and weakly lsc. In this paper, we generalize the concept of weak semicontinuity [1, 3] to the case of unbounded operators affiliated with $A^**$. Also we consider the generalized version of the conditions of the Brown's theorem [3, Proposition 2.2 & 3.27] for unbounded operators.

Keywords

References

  1. Duke Math. J. v.40 Complications of semicontinuity in $C^*$ -algebra theory C. A. Akemann;G. K. Pedersen
  2. J. Funct. Anal. v.13 Multipliers of $C^*$ ­algebras C. A. Akemann;G. K. Pedersen;J. Tomiyama
  3. Canad. J. Math. v.40 Semicontinuity and multipliers of C_­algebras L. G. Brown
  4. Some automatic continuity theorems for operator algebras and centralizers of Pedersen's ideal(preprint) L. G. Brown
  5. Trans. Amer. Math. Soc. v.32 Double centralizers and extensions of $C^*$ ­algebras R. C. Busby
  6. Rings of continuous functions L. Gillman;M. Jerison
  7. Math. Scand. v.15 The range of certain convolution operators E. Hewitt
  8. Proc. London Math. Soc. v.14 An introduction to the theory of centralizers B. Johnson
  9. Rocky Mount. J. Math. v.25 Strong semicontinuity for unbounded operators H. Kim
  10. Middle semicontinuity for unbounded operators(preprint) H. Kim
  11. Memoirs Amer. Math. Soc. v.169 Multipliers of Pedersen's ideal A. J. Lazar;D. C. Taylor
  12. The spectrum of a PCSalgebra(preprint) J. Mack
  13. Duke Math. J. v.22 Applications of $weak^*$ semicontinuity in $C^*$ ­algebra theory G. K. Pedersen
  14. $C^*$ ­algebras and their automorphism groups G. K. Pedersen
  15. Proc. Amer. Math. v.104 A new approach to the multipliers of Pedersen's ideal N. C. Phillips