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61.
György Gát 《Analysis Mathematica》2006,32(1):25-48
Summary It is known that the Fejér means - with respect to the character system of the Walsh, and bounded Vilenkin groups - of an
integrable function converge to the function a.e. In this work we discuss analogous problems on the complete product of finite,
not necessarily Abelian groups with respect to the character system for functions that are constant on the conjugacy classes.
We find that the nonabelian case differs from the commutative case. We prove the a.e. convergence of the (C,1) means of the Fourier series of square integrable functions. We also prove the existence of a function f∊Lq for some q >1 such that sup |σn f | = + ∞ a.e. This is a sharp contrast between the Abelian and the nonabelian cases. 相似文献
62.
63.
Magnus B. Landstad 《Journal of Functional Analysis》2002,191(2):211-223
We study properties of C*-algebraic deformations of homogeneous spaces G/Γ which are equivariant in the sense that they preserve the natural action of G by left translation. The center is shown to be isomorphic to C(G/G0ρ) for a certain subgroup G0ρ of G, and there is a 1-1 correspondence between normalised traces and probability measures on G/G0ρ. This makes it possible to represent the deformed algebra as operators over L2(G/Γ). Applications to K-theory are also mentioned. 相似文献
64.
Jürg Fröhlich Tai-Peng Tsai Horng-Tzer Yau 《Communications in Mathematical Physics》2002,225(2):223-274
We consider the nonlinear Hartree equation describing the dynamics of weakly interacting non-relativistic Bosons. We show
that a nonlinear M?ller wave operator describing the scattering of a soliton and a wave can be defined. We also consider the dynamics of a
soliton in a slowly varying background potential W(ɛx). We prove that the soliton decomposes into a soliton plus a scattering wave (radiation) up to times of order ɛ−1. To leading order, the center of the soliton follows the trajectory of a classical particle in the potential W(ɛx).
Received: 30 June 2000 / Accepted: 25 June 2001 相似文献
65.
Jörg Zintl 《Mathematische Zeitschrift》2002,242(3):415-426
66.
A cutting plane algorithm for a clustering problem 总被引:2,自引:0,他引:2
In this paper we consider a clustering problem that arises in qualitative data analysis. This problem can be transformed to a combinatorial optimization problem, the clique partitioning problem. We have studied the latter problem from a polyhedral point of view and determined large classes of facets of the associated polytope. These theoretical results are utilized in this paper. We describe a cutting plane algorithm that is based on the simplex method and uses exact and heuristic separation routines for some of the classes of facets mentioned before. We discuss some details of the implementation of our code and present our computational results. We mention applications from, e.g., zoology, economics, and the political sciences. 相似文献
67.
68.
In contrast to stochastic differential equation models used for the calculation of the term structure of interest rates, we
develop an approach based on linear dynamical systems under non-stochastic uncertainty with perturbations. The uncertainty
is described in terms of known feasible sets of varying parameters. Observations are used in order to estimate these parameters
by minimizing the maximum of the absolute value of measurement errors, which leads to a linear or nonlinear semi-infinite
programming problem. A regularized logarithmic barrier method for solving (ill-posed) convex semi-infinite programming problems
is suggested. In this method a multi-step proximal regularization is coupled with an adaptive discretization strategy in the
framework of an interior point approach. A special deleting rule permits one to use only a part of the constraints of the
discretized problems. Convergence of the method and its stability with respect to data perturbations in the cone of convexC
1-functions are studied. On the basis of the solutions of the semi-infinite programming problems a technical trading system
for future contracts of the German DAX is suggested and developed.
Supported by the Stiftung Rheinland/Pfalz für Innovation, No. 8312-386261/307. 相似文献
69.
The tunneling of single electrons in small capacitance tunnel junctions is influenced by charging effects and by the fluctuations of the elecromagnetic environment. We study the effect of an external circuit with arbitrary impedance on the tunneling of quasiparticles and Cooper pairs in voltage driven Josephson junctions. We present results at finite temperatures and also consider an acdriven system. 相似文献
70.
E. Possenriede P. Jacobs H. Kröse O. F. Schirmer 《Applied Physics A: Materials Science & Processing》1992,55(1):73-81
On the basis of a previous identification of paramagnetic defects in nominally undoped as grown BaTiO3 single crystals, we have investigated the changes of the concentrations of these centers and their optical absorptions under illumination with light of varying wavelengths. The most pronounced charge transfers occur by hole ionization of Fe4+ and — to a lesser extent — of Cr5+ and Cr4+. At low temperatures the created holes are trapped in the form of O–-ions next to Al3+ or unknown acceptor defects. Corresponding Fe4+ and O– absorptions have been identified. 相似文献