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951.
Jakob G. Heller Nikolai Neumaier Stefan Waldmann 《Letters in Mathematical Physics》2007,80(3):257-272
Locally noncommutative spacetimes provide a refined notion of noncommutative spacetimes where the noncommutativity is present
only for small distances. Here we discuss a non-perturbative approach based on Rieffel’s strict deformation quantization.
To this end, we extend the usual C
*-algebraic results to a pro-C
*-algebraic framework.
相似文献
952.
The aim of this note is to understand under which conditions invertible modules over a commutative -algebra in the sense of Elmendorf, Kriz, Mandell & May give rise to elements in the algebraic Picard group of invertible graded modules over the coefficient ring by taking homotopy groups. If a connective commutative -algebra R has coherent localizations for every maximal ideal , then for every invertible R-module U, U*=π*U is an invertible graded R*-module. In some non-connective cases we can carry the result over under the additional assumption that the commutative -algebra has ‘residue fields’ for all maximal ideals if the global dimension of R* is small or if R is 2-periodic with underlying Noetherian complete local regular ring R0. We apply these results to finite abelian Galois extensions of Lubin-Tate spectra. 相似文献
953.
The elements of various algebras of stable degree zero operations in p-local K-theory can be described explicitly as certain infinite sums of Adams operations [11, 9]. Here we show how to make sense of
the same expressions for MU(p) and BP, thus identifying the “Adams subalgebra” of the algebras of operations. We prove that the Adams subalgebra is the centre
of the ring of degree zero operations. 相似文献
954.
H. Winkler 《Integral Equations and Operator Theory》2000,38(2):222-250
We consider a singular two-dimensional canonical systemJy=–zHy on [0, ) such that at Weyl's limit point case holds. HereH is a measurable, real and nonnegative definite matrix function, called Hamiltonian. From results of L. de Branges it follows that the correspondence between canonical systems and their Titchmarsh-Weyl coefficients is a bijection between the class of all Hamiltonians with trH=1 and the class of Nevanlinna functions. In this note we show how the HamiltonianH of a canonical system changes if its Titchmarsh-Weyl coefficient or the corresponding spectral measure undergoes certain small perturbations. This generalizes results of H. Dym and N. Kravitsky for so-called vibrating strings, in particular a generalization of a construction principle of I.M. Gelfand and B.M. Levitan can be shown. 相似文献
955.
Simple expansions and expansions by point finite and locally finite collections are studied for particular classes of k-spaces. All such expansions of Fréchet spaces are shown to be Fréchet, and sufficient conditions for the preservation of property P ? {k1, sequential, k} under simple and locally finite expansions are established. 相似文献
956.
Simeon M. Berman 《Stochastic Processes and their Applications》1981,12(1):1-26
A new class of stochastic processes, called processes of positive bivariate type, is defined. Such a process is typically one whose bivariate density functions are positive definite, at least for pairs of time points which are sufficiently mutually close. The class includes stationary Gaussian processes and stationary reversible Markov processes, and is closed under the operations of composition and convolution. The purpose of this work is to show that the local times of such processes can be investigated in a natural way. One of the main contributions is an orthogonal expansion of the local time which is new even in the well-studied stationary Gaussian case. The basic tool in its construction is the Lancaster-Sarmanov expansion of a bivariate density in a series of canonical correlations and canonical variables. 相似文献
957.
958.
959.
Tyan and Thomas (J. Multivariate Anal.5 (1975), 227–235), have given a characterization of a class of bivariate distributions which yields, as a special case, a characterization of a class of bivariate Poisson distributions. In this paper we develop an analogous characterization of a class of bivariate Poisson processes and give some properties and examples of such processes. 相似文献
960.