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1.
Normal operators similar to irreducible operators 总被引:1,自引:0,他引:1
A complete characterization of normal operators which are similar to irreducible operators and some related results are given. 相似文献
2.
Let T be a bounded linear operator on Hilbert space H, M an invariant subspace of T. If there exists another invariant subspace N of T such that H = M + N and M ∩ N = 0, then M is said to be a completely reduced subspace of T. If T has a nontrivial completely reduced subspace, then T is said to be completely reducible; otherwise T is said to be completely irreducible. In the present paper we briefly sum up works on completely irreducible operators that
have been done by the Functional Analysis Seminar of Jilin University in the past ten years and more.
The paper contains four sections. In section 1 the background of completely irreducible operators is given in detail. Section
2 shows which operator in some well-known classes of operators, for example, weighted shifts, Toeplitz operators, etc., is
completely irreducible. In section 3 it is proved that every bounded linear operator on the Hilbert space can be approximated
by the finite direct sum of completely irreducible operators. It is clear that a completely irreducible operator is a rather
suitable analogue of Jordan blocks in L(H), the set of all bounded linear operators on Hilbert space H. In section 4 several questions concerning completely irreducible operators are discussed and it is shown that some properties
of completely irreducible operators are different from properties of unicellular operators.
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Translated from Acta Sci. Nat. Univ. Jilin, 1992, (4): 20–29 相似文献
3.
This paper firstly discusses the existence of strongly irreducible operators on Banach spaces. It shows that there exist strongly
irreducible operators on Banach spaces with w*-separable dual. It also gives some properties of strongly irreducible operators on Banach spaces. In particular, if T is a strongly irreducible operator on an infinite-dimensional Banach space, then T is not of finite rank and T is not an algebraic operator. On Banach spaces with subsymmetric bases, including infinite-dimensional separable Hilbert
spaces, it shows that quasisimilarity does not preserve strong irreducibility. In addition, we show that the strong irreducibility
of an operator does not imply the strong irreducibility of its conjugate operator, which is not the same as the property in
Hilbert spaces. 相似文献
4.
Nathan S. Feldman Paul McGuire 《Proceedings of the American Mathematical Society》2003,131(6):1793-1801
In this paper we show that the spectral picture of an irreducible subnormal operator may be arbitrarily prescribed subject only to certain natural necessary conditions. This completes work begun by the second author.
5.
Herrero’s conjecture that each operator with connected spectrum acting on complex, separable Hilbert space can be written
as the sum of a strongly irreducible operator and a compact operator is proved.
Jiang, C. L., Power, S., Wang, Z. Y., Biquasitriangular + small compact = strongly irreducible,J. London Math., to be published. 相似文献
6.
We show, in particular, that in the class of minimax two-step nilpotent groups only finitely generated groups can admit exact irreducible primitive representations over a finitely generated field of characteristic zero. We also suggest some approaches to studying induced representations of nilpotent groups of finite rank. 相似文献
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10.
江治杰 《纯粹数学与应用数学》2010,26(6):984-991
通过再生核函数刻画了Hardy空间,Bergman空间上自伴加权复合算子以及自伴等距加权复合算子,最后研究了单位球上的分式线性自同构,得到了一个充分条件。 相似文献
11.
Spectral Properties of Second Order Differential Operators on Two-step Nilpotent Lie Groups 下载免费PDF全文
In this paper, spectral properties of certain left invariant differential operators on two-step nilpotent Lie groups are completely described by using the theory of unitary irreducible representations and the Plancherel formulae on nilpotent Lie groups. 相似文献
12.
Let S be an antinegative commutative semiring without zero divisors and M_n(S)be the semiring of all n×n matrices over S.For a linear operator L on M_n(S),we say that L strongly preserves nilpotent matrices in M_n(S)if for any A∈M_n(S),A is nilpotent if and only if L(A)is nilpotent.In this paper,the linear operators that strongly preserve nilpotent matrices over S are characterized. 相似文献
13.
V. A. Derkach 《Mathematical Notes》1998,63(4):449-459
The Laguerre-Sonin polynomialsL
n
()
are orthogonal in linear spaces with indefinite inner product if<–1. We construct the completion () of this space and describe self-adjoint extensions of the Laguerre operatorl(y)=xy+(1+–x)y,<–1, in the space (). In particular, we write out the self-adjoint extension of the Laguerre operator whose eigenfunctions coincide with the Laguerre-Sonin polynomials and form an orthogonal basis in ().Translated fromMatematicheskie Zametki, Vol. 63, No. 4, pp. 509–521, April, 1998.This research was partially supported by the INTAS foundation under grant No. 93-02449. 相似文献
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S. I. Kadchenko 《Computational Mathematics and Mathematical Physics》2007,47(9):1435-1445
A new method is proposed and validated for computing the sums of number series of discrete operators in perturbation theory with the required accuracy. Its efficiency is demonstrated through numerical computations. 相似文献
16.
In this paper, we consider differential operators of 2nd-order
a[u]=(-1)k(ak(x)u(k)(x))(k), x∈(0, ∞)
whose coefficients ak(x) are restricted by powers of ex, and give conditions on the coefficients sufficient to ensure that the spectrum is discrete; next we formulate necessary and sufficient conditions for the discreteness of the spectrum of differential operators whose coefficients ak(x) may increase as eαkx as x→∞. 相似文献
17.
In this paper, we first establish an abstract inequality for lower order eigenvalues of a self-adjoint operator on a Hilbert space which generalizes and extends the recent results of Cheng et al. (Calc. Var. Partial Differential Equations, 38, 409-416 (2010)). Then, making use of it, we obtain some universal inequalities for lower order eigenvalues of the biharmonic operator on manifolds admitting some speciM functions. Moreover, we derive a universal inequality for lower order eigenvalues of the poly-Laplacian with any order on the Euclidean space. 相似文献
18.
Under the assumption of the product τ:=l+l of the regular differential expression l and its adjoint l+, being well-formed, a complete characterization of all the positive self-adjoint extensions of the minimal operator generated by τ in terms of boundary conditions is given. 相似文献
19.
K. D. Magill Jr 《Southeast Asian Bulletin of Mathematics》2002,25(3):443-456
We find all multiplications on the two dimensional Euclidean group (IR2,+) such that (IR2, +, ·) is a nilpotent topological nearring of rank three. We determine the left, right, and two sided ideals of these nearrings and we determine when two of these nearrings are isomorphic. As a consequence, we are able to conclude that there are infinitely many isomorphism classes of such nearrings. This is in considerable contrast to the case for rings. There are only eight isomorphism classes of topological rings with additive group (IR2,+).AMS Subject Classification (2000)
16Y30 相似文献