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81.
A. V. Lebedev 《Functional Analysis and Its Applications》2005,39(3):207-214
We study the relationship between the topological freeness of partial actions of discrete groups and faithful representations of the corresponding crossed products. 相似文献
82.
WenMing Wu 《中国科学A辑(英文版)》2008,51(11):2081-2088
Given the hyperbolic measure dxdy/y
2 on the upper half plane ℍ, the rational actions of PSL2(ℝ) on ℍ induces a continuous unitary representation α of this group on the Hilbert space L
2(ℍ, dxdy/y
2). Supposing that = {M
f
: f ∈ L
∞ (ℍ, dxdy/y
2)}, we show that the crossed product is of type I. In fact, the crossed product is *-isomorphic to the von Neumann algebra , where is the abelian group von Neumann algebra generated by the left regular representation of K.
This work was supported by the Youth Foundation of Sichuan Education Department of China (Grant No. 2003B017) 相似文献
83.
Ruy Exel 《Bulletin of the Brazilian Mathematical Society》2008,39(2):191-313
We describe a special class of representations of an inverse semigroup S on Hilbert's space which we term tight. These representations are supported on a subset of the spectrum of the idempotent semilattice of S, called the tight spectrum, which is in turn shown to be precisely the closure of the space of ultra-filters, once filters are identified with semicharacters
in a natural way. These representations are moreover shown to correspond to representations of the C*-algebra of the groupoid
of germs for the action of S on its tight spectrum. We then treat the case of certain inverse semigroups constructed from
semigroupoids, generalizing and inspired by inverse semigroups constructed from ordinary and higher rank graphs. The tight
representations of this inverse semigroup are in one-to-one correspondence with representations of the semigroupoid, and consequently
the semigroupoid algebra is given a groupoid model. The groupoid which arises from this construction is shown to be the same
as the boundary path groupoid of Farthing, Muhly and Yeend, at least in the singly aligned, sourceless case.
*Partially supported by CNPq. 相似文献
84.
In this paper we further develop the theory of one-sided shift spaces over infinite alphabets, characterizing one-step shifts as edge shifts of ultragraphs and partially answering a conjecture regarding shifts of finite type (we show that there exist shifts of finite type that are not conjugate, via a conjugacy that is eventually finite periodic, to an edge shift of a graph). We also show that there exist edge shifts of ultragraphs that are shifts of finite type, but are not conjugate to a full shift, a result that is not true for edge shifts of graphs. One of the key results needed in the proofs of our conclusions is the realization of a class of ultragraph C*-algebras as partial crossed products, a result of interest on its own. 相似文献
85.
86.
87.
《Optimization》2012,61(4):543-553
A model of optimal control for discrete systems and the historical development of the discrete maximum principle are considered. The paper deals with local optimality conditions of the first order, e.g. with a local maximum-principle and a quasi-maximum principle. Furthermore, optimality conditions of higher order, e. g. an optimality condition for singular controls are given. 相似文献
88.
化学反应过渡态决定了包括反应速率和微观反应动力学在内的化学反应的基本特性,而无论是从理论还是实验上研究和观测化学反应过渡态都是极具挑战性的课题.近年来,我国科学家们利用交叉分子束-里德堡氢原子飞行时间谱仪,结合高精度的量子动力学计算,对H+H2和F+H2这两个教科书式的典型反应体系进行了全量子态分辨的反应动力学研究,从中得出了关于这两个反应体系的过渡态的结构和动力学性质的结论性的研究成果. 相似文献
89.
Summary The deformation of thick sheet metal is analyzed using 3D coordinates of cross-gratings on both sides of a specimen. The
basic equations are presented for evaluating the 3D strain tensor from displacement functions. Provided the grating coordinates
are measured in the undeformed and the deformed states, the difference of the coordinates yields displacement vectors. These
are used to determine polynomial displacement functions, which approximate the displacement vectors in a least-squares sense.
The condition of volume invariance at plastic deformation implies the strain in the direction of the thickness. The whole
procedure is tested by a radial symmetric forming of a rectangular sheet metal into a half-tube, because it can be evaluated
analytically, too. Finally, a real forming process of a plane circular sheet metal into a cup-like object is analyzed.
Received 10 May 1999; accepted for publication 22 September 1999 相似文献
90.