共查询到20条相似文献,搜索用时 0 毫秒
1.
Li Jiankui 《Integral Equations and Operator Theory》1997,29(1):110-115
We show that many of the features of the theory of hypercyclic and supercyclic operators extend to that of finitely hypercyclic/supercyclic operators. In particular, subnormal operators, Banach space isometries, and thereforeC
1 contractions are not finitely supercyclic. 相似文献
2.
Let U be the unilateral shift on ?2. For any complex numbers α and β, put T = αU + βU* and S = T 2. Then we show that the operator S is convexoid. 相似文献
3.
A. Seddik 《Integral Equations and Operator Theory》2002,43(2):248-252
For n-tuplesA=(A
1,...,A
n
) andB=(B
1,...,B
n
) of operators on a Hilbert spaceH, letR
A,B
denote the operator onL(H) defined by
. In this paper we prove that
whereW is the joint spatial numerical range andW
0 is the numerical range. We will show also that this inclusion becomes an equality whenR
A,B
is taken to be a generalized derivation, and it is strict whenR
A,B
is taken to be an elementary multiplication operator induced by non scalar self-adjoints operators. 相似文献
4.
M. Barraa 《Proceedings of the American Mathematical Society》2005,133(6):1723-1726
Let and denote two -tuples of operators with and Let denote the elementary operators defined on the Hilbert-Schmidt class by We show that
Here is the essential numerical range, is the joint numerical range and is the joint essential numerical range.
Here is the essential numerical range, is the joint numerical range and is the joint essential numerical range.
5.
6.
Jean Bourgain 《Israel Journal of Mathematics》1992,79(2-3):193-206
In this paper, new results are obtained concerning the uniform approximation property (UAP) inL
p-spaces (p≠2,1,∞). First, it is shown that the “uniform approximation function” does not allow a polynomial estimate. This fact is rather
surprising since it disproves the analogy between UAP-features and the presence of “large” euclidian subspaces in the space
and its dual. The examples are translation invariant spaces on the Cantor group and this extra structure permits one to replace
the problem with statements about the nonexistence of certain multipliers in harmonic analysis. Secondly, it is proved that
the UAP-function has an exponential upper estimate (this was known forp=1, ∞). The argument uses Schauder’s fix point theorem. Its precise behaviour is left unclarified here. It appears as a difficult
question, even in the translation invariant context. 相似文献
7.
This paper is a recapitulation of the work of L. Szili and P. Vértesi [4] on multivariate Fourier series with triangular type partial sums. Namely, we give another proof for the corresponding lower estimation, which, in a way, is more direct than the previous one in [4]. 相似文献
8.
9.
I. Glicksberg 《Israel Journal of Mathematics》1965,3(2):71-74
Results of Rosenblatt on almost periodic transition operators are extended to the reducible case. 相似文献
10.
Dragoljub Keckic 《Proceedings of the American Mathematical Society》2000,128(11):3369-3377
We prove the orthogonality of the range and the kernel of an important class of elementary operators with respect to the unitarily invariant norms associated with norm ideals of operators. This class consists of those mappings , , where is the algebra of all bounded Hilbert space operators, and , , , are normal operators, such that , and . Also we establish that this class is, in a certain sense, the widest class for which such an orthogonality result is valid. Some other related results are also given.
11.
J. Bourgain 《Israel Journal of Mathematics》1992,77(1-2):1-16
We study the almost everythere convergence to the initial dataf(x)=u(x, 0) of the solutionu(x, t) of the two-dimensional linear Schrödinger equation Δu=i? t u. The main result is thatu(x, t) →f(x) almost everywhere fort → 0 iff ∈H p (R2), wherep may be chosen <1/2. To get this result (improving on Vega’s work, see [6]), we devise a strategy to capture certain cancellations, which we believe has other applications in related problems. 相似文献
12.
Yeneng Sun 《Archiv der Mathematik》1994,63(6):530-534
13.
14.
I. Glicksberg 《Israel Journal of Mathematics》1969,7(2):147-150
For a transition operator onC(X) with an invariant measure having global support, the point spectrum of unit modulus and the corresponding eigenfunctions
are related to the action of a compact group on a quotient space ofX.
Work supported in part by the National Science Foundation. 相似文献
15.
16.
Zhang Weiping 《数学学报(英文版)》1993,9(3):240-245
In this paper, we prove the regularity near the origin of the ν-function of Dirac operators associated with certain non-torsion
free connections. 相似文献
17.
18.
S. V. Tishchenko 《Ukrainian Mathematical Journal》1997,49(6):984-987
We prove that two self-adjoint operators that anticommute on the dense invariant domain of their common quasianalytic vectors
are strongly anticommuting.
Kiev University, Kiev. Translated from Ukrainskii Matematicheskii, Zhurnal, Vol. 49, No. 6. pp. 878–880, June, 1997. 相似文献
19.
20.
Hong-Ke Du Yue-Qing Wang Gui-Bao Gao 《Proceedings of the American Mathematical Society》2008,136(4):1337-1348
Let and , , be bounded linear operators acting on a separable Hilbert space . In this note, we prove that Moreover, we prove that there exists an operator with such that if and only if there exists a unitary such that