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91.
We continue our study of operator algebras with contractive approximate identities (cais) by presenting a couple of interesting examples of operator algebras with cais, which in particular answer questions raised in previous papers in this series, for example about whether, roughly speaking, ‘weak compactness’ of an operator algebra, or the lack of it, can be seen in the spectra of its elements. 相似文献
92.
We prove that every closed subgroup of a locally compact group is locally p -Ditkin for 1<p<∞. 相似文献
93.
94.
Kaufman?s theorem (Kaufman, 1978 [9]) on representing closed linear operators as quotients of bounded operators is given a new constructive proof, and is extended to operators between two Hilbert spaces. Two different definitions of operator quotients existing in the literature are compared. 相似文献
95.
Let f(t) be an operator monotone function. Then A?B implies f(A)?f(B), but the converse implication is not true. Let A?B be the geometric mean of A,B?0. If A?B, then B−1?A?I; the converse implication is not true either. We will show that if f(λB+I)−1?f(λA+I)?I for all sufficiently small λ>0, then f(λA+I)?f(λB+I) and A?B. Moreover, we extend it to multi-variable matrices means. 相似文献
96.
97.
In this paper, we study groups of positive operators on Banach lattices. If a certain factorization property holds for the elements of such a group, the group has a homomorphic image in the isometric positive operators which has the same invariant ideals as the original group. If the group is compact in the strong operator topology, it equals a group of isometric positive operators conjugated by a single central lattice automorphism, provided an additional technical assumption is satisfied, for which we have only examples. We obtain a characterization of positive representations of a group with compact image in the strong operator topology, and use this for normalized symmetric Banach sequence spaces to prove an ordered version of the decomposition theorem for unitary representations of compact groups. Applications concerning spaces of continuous functions are also considered. 相似文献
98.
王胜华 《上饶师范学院学报》1998,(3)
本文研究了板模型中一类具反射边界条件、各向同性、单能、非均匀介质的中子迁移算子的谱,证明了在右半平面中,该算子仅有有限个具有限代数重数的实离散本征值 相似文献
99.
We present a new simple proof of the structural result for elementary operators on standard operator algebras. Using the idea of this short proof we can characterize surjective maps between standard operator algebras having a certain multiplicativity-like property appearing in the abstract definition of elementary operators of length one. In particular, we show that such maps are automatically additive. 相似文献
100.