The strongly irreducible operators in nest algebras

Springer Science and Business Media LLC - Tập 28 - Trang 28-44 - 1997
You Qing Ji1, Chun Lan Jiang1, Zong Yao Wang2
1Department of Mathematics, Jilin University, Changchun, Peoples Republic of China
2Department of Mathematics, East China University of Science and Technology, Shanghai, Peoples Republic of China

Tóm tắt

An operatorT on $$\mathcal{H}$$ is called strongly irreducible ifT does not commute with any nontrivial idempotent operator. In this paper, we first show that each nest algebra τ( $$\mathcal{N}$$ ) has strongly irreducible operators. Secondly, we obtain a characterization of operators which can be uniquely written as a direct sum of finitely many strongly irreducible operators. Finally, we characterize the strongly irreducibility of operators in a nest algebra τ( $$\mathcal{N}$$ ).

Tài liệu tham khảo

[Bar-Dav] J. Barria and K.R. Davidson, Unicellar operators, Trans. Amer. Math. Soc., (284) 1984, 229–246.

[Dav] K.R. Davidson, Nest algebra, Pitman Res., Notes Math. 191, Longman Harlow, Essex, 1988.

[Dix] J. Dixmier, Les operateurs permutables a loperateur integral, Fas. 2, Portugal Math. (8) 1949, 73–84.

[Don] W.F. Donoghue, The lattice of invariant subspaces of a completly continuous quasinilpotent transformation, Pacific J. Math., 1957, 1031–1035.

[Fia] L.A. Fialkow, A note on the range of the operatorX → AX-XB, Illinois J. Math., (25), 1981, 112–124.

[Fon-Jia] C.K. Fong and Jiang, C.L., Approximation by Jordan type operators, Houston J. Math., (19) 1993, 51–62.

[Gil] F. Gilfeather, Strong reducibility of operators, Ind. Univ. Math. J., (22), 1972, 393–397.

[Har-Lon] K.J. Harrison and W.E. Longstaff, An invariant subspace lattice of order typew+w+1, Proc. Amer. Math., (79), 1980, 45–49.

[Her] D.A. Herrero, Approximation of Hilbert space operators, Pitman Res., Notes Math., 224, Longman Harlow, Essex, 1990.

[Her-Jia] D.A. Herrero and C.L. Jiang, Limits of strongly irreducible operators and the Riesz decomposition theorem, Mich. Math. J., (37), 1990, 283–291.

[Ji-Jia-Wan] Y.Q. Ji, C.L. Jiang, Z.Y. Wang, Essentially normal+small compact=strongly irreducible, Chinese Journal of Comtemporary Mathematics (to appear).

[Jia] Z.J. Jiang, Topics in operator theory, Seminar Reports in Functional analysis, Jilin University, Changchung (in chinese), 1979.

[Jia] C.L. Jiang, Similarity Reducibility and Approximation of the Cowen-Douglas operators, J. Operator Theory 32, 1994, 77–89.

[Jia-Wan] C.L. Jiang and Z.Y. Wang, A class of strongly irreducible operators with nice properties, J. Operator Theory (to appear).

[Nik] N.K. Nikolskii, Selected problems of weighted approximation and spectral analysis, Proc. Steklov. Inst. Math., (120), 1974, Amer. Math. Soc., Providence, 1976.

[Yak] B.V. Yakubovic, Invariant subspaces of weighted shift operators, Zapiski Nauk. Sem. Lomi., (141) 1985, 100–143.