共查询到20条相似文献,搜索用时 156 毫秒
1.
Up to derived equivalence, the representation-finite self-injective algebras of class A
n are divided into the wreath-like algebras (containing all Brauer tree algebras) and the Möbius algebras. In Part I (Forum Math.
11 (1999), 177–201), the ring structure of Hochschild cohomology of wreath-like algebras was determined, the key observation being that kernels in a minimal bimodule resolution of the algebras are twisted bimodules. In this paper we prove that also for Möbius algebras certain kernels in a minimal bimodule resolution carry the structure of a twisted bimodule. As an application we obtain detailed information on subrings of the Hochschild cohomology rings of Möbius algebras. 相似文献
2.
Weiyi Su 《Journal of Approximation Theory》1986,47(4)
At present there are only a few approximate identity kernels for the Walsh system, for example, the pN-truncated Dirichlet kernel DpN − 1(t) = ∑j = 0pN − 1 wj(t) [6]; the Abel-Poisson kernel λγ(t) = ∑k = 0∞ γkwk(t) [3], and so on. In [6], Zheng has introduced a new kind of approximate identity kernels for the Walsh system—the kernels of product type. In the present paper we discuss the approximation properties of such product type kernels. Estimates of their moments as well as a direct approximation theorem are obtained. Then, to establish an inverse approximation theorem, we need the p-adic derivative of product type kernels and we estimate this derivative in L1-norm. 相似文献
3.
Hubert Hennion 《Probability Theory and Related Fields》2007,139(3-4):451-471
We show how the essential spectral radius r
e
(Q) of a bounded positive kernel Q, acting on bounded functions, is linked to the lower approximation of Q by certain absolutely continuous kernels. The standart Doeblin’s condition can be interpreted in this context, and, when
suitably reformulated, it leads to a formula for r
e
(Q). This results may be used to characterize the Markov kernels having a quasi-compact action on a space of measurable functions
bounded with respect to some test function, when no irreducibilty and aperiodicity are assumed.
相似文献
4.
We give new sufficient conditions for kernels to belong to the set C
y,2n
introduced by Kushpel'. These conditions give the possibility of extending the set of kernels belonging to C
y,2n
. On the basis of these results, we obtain lower bounds for the Kolmogorov widths of classes of convolutions with these kernels. We show that these estimates are exact in certain important cases.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 47, No. 8, pp. 1112–1121, August, 1995. 相似文献
5.
For a positive integer n let Cl0,n be the universal Clifford algebra with the signature (0,n). The name Clifford analysis is usually referred to the function theories for functions in the kernels of the two operators: the (Cliffordian) Cauchy–Riemann operator and the Dirac operator. For n=2, Cl0,2 becomes the skew‐field of Hamilton's quaternions for which the two operators are widely known: the Moisil–Théodoresco and the Fueter operators. We establish the precise relations between the Moisil–Théodoresco operator and the Dirac operator for Cl0,3. It turns out that the case of the Cauchy–Riemann operator for Cl0,3 and the Fueter operator is more sophisticated, and we describe the peculiarities emerging here. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
6.
A. Shchuplev A. Tsikh A. Yger 《Proceedings of the Steklov Institute of Mathematics》2006,253(1):256-274
A finite collection of planes {E
v
} in ℂd is called an atomic family if the top de Rham cohomology group of its complement is generated by a single element. A closed
differential form generating this group is called a residual kernel for the atomic family. We construct new residual kernels
in the case when E
v
are coordinate planes such that the complement ℂd/∪ E
v
admits a toric action with the orbit space being homeomorphic to a compact projective toric variety. They generalize the
well-known Bochner-Martinelli and Sorani differential forms. The kernels obtained are used to establish a new formula of integral
representations for functions holomorphic in Reinhardt polyhedra. 相似文献
7.
Ulrich Tippenhauer 《Journal of Approximation Theory》1977,21(4):394-410
Methods to determine reproducing kernels. The explicit representation of continuous linear functionals on a Hilbert space by reprokernels is significant for interpolation and approximation. Starting with the kernels theorem, due to Schwartz, we develop methods to determine reprokernels for the Sobolev spaces W2k(Ω) if Ω R1, and for some subspaces of W2k(Ω) if ΩRn. Then we determine reprokernels for tensor products of Hilbert spaces. In addition to this we consider three types of limits of reprokernels. 相似文献
8.
It is well known that it is possible to enhance the approximation properties of a kernel operator by increasing its support size. There is an obvious tradeoff between higher approximation order of a kernel and the complexity of algorithms that employ it. A question is then asked: how do we compare the efficiency of kernels with comparable support size? We follow Blu and Unser and choose as a measure of the efficiency of the kernels the first leading constant in a certain error expansion. We use time domain methods to treat the case of globally supported kernels in L p (R d), 1≤p≤∞.
相似文献9.
We consider a class of multidimensional potential‐type operators with kernels that have singularities at the origin and on the unit sphere and that are oscillating at infinity. We describe some convex sets in the (1/p, 1/q)‐plane for which these operators are bounded from Lp into Lq and indicate domains where they are not bounded. We also reveal some effects which show that oscillation and singularities of the kernels may strongly influence on the picture of boundedness of the operators under consideration. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
10.
Prof. Dr. U. Rieder 《Mathematical Methods of Operations Research》1991,35(6):473-490
A general partially observed control model with discrete time parameter is investigated. Our main interest concerns monotonicity results and bounds for the value functions and for optimal policies. In particular, we show how the value functions depend on the observation kernels and we present conditions for a lower bound of an optimal policy. Our approach is based on two multivariate stochastic orderings: theTP
2 ordering and the Blackwell ordering.Dedicated to Prof. Dr. K. Hinderer on the occassion of his 60th birthday 相似文献
11.
It is often observed that interpolation based on translates of radial basis functions or non-radial kernels is numerically
unstable due to exceedingly large condition of the kernel matrix. But if stability is assessed in function space without considering
special bases, this paper proves that kernel-based interpolation is stable. Provided that the data are not too wildly scattered,
the L
2 or L
∞ norms of interpolants can be bounded above by discrete ℓ2 and ℓ ∞ norms of the data. Furthermore, Lagrange basis functions are uniformly bounded and Lebesgue constants grow at most like the
square root of the number of data points. However, this analysis applies only to kernels of limited smoothness. Numerical
examples support our bounds, but also show that the case of infinitely smooth kernels must lead to worse bounds in future
work, while the observed Lebesgue constants for kernels with limited smoothness even seem to be independent of the sample
size and the fill distance. 相似文献
12.
Some results that have been obtained in the study of strongly and weakly ergodic behavior of non-homogeneous stochastic kernels
are generalized to the case of non-negative kernels. The first generalization simply involves extending the definitions of
weakly and strongly ergiodic behavior to the case of non-negative kernels and using the ergodic coefficient which was first
defined for stochastic kernels by Dobrushin and extended to non-negative kernels by Blum and Reichaw. It happens that this
straightforward extension excludes many cases of non-negative kernels which do exhibit a types of ergodic behavior. In order
to study these cases a definition ofL
1 weakly and strongly ergodic behavior is given in which normalizing by constants is allowed. Sufficient conditions for these
types of ergodic behavior are given. 相似文献
13.
In this paper we look at the theory of reproducing kernels for spaces of functions in a Clifford algebra
0, n. A first result is that reproducing kernels of this kind are solutions to a minimum problem, which is a non-trivial extension of the analogous property for real and complex valued functions. In the next sections we restrict our attention to Szegö and Bergman modules of monogenic functions. The transformation property of the Szegö kernel under conformal transformations is proved, and the Szegö and Bergman kernels for the half space are calculated. 相似文献
14.
《代数通讯》2013,41(4):1073-1081
ABSTRACT In this paper, it is proved that if F is a global field, then for any integer n > 3, there is an extension field E over F of degree n such that K 2 E is not generated by the Steinberg symbols {a, b} with a ∈ F*, b, ∈ E*. If however, F is a number field and D is a finite-dimensional central division F-algebra with square free index, then K 2 D is always generated by the Steinberg symbols {a, b} with a ∈ F*, b ∈ D*. Finally, the tame kernels of central division algebras over F are expressed explicitly. 相似文献
15.
Josefina Alvarez Martha Guzmn-Partida 《Journal of Mathematical Analysis and Applications》2002,270(2):235-434
We characterize those tempered distributions which are S′-convolvable with a given class of singular convolution kernels. We study both, the Euclidean case and the product domain case. In the Euclidean case, we consider a class of kernels that includes Riesz kernels, Calderón–Zygmund singular convolution kernels, finite part distributions defined by hypersingular convolution kernels, and Hörmander multipliers. In the product domain case, we consider a class of singular kernels introduced by Fefferman and Stein as a generalization of the n-dimensional Hilbert kernel. 相似文献
16.
O. G. Avsyankin 《Differential Equations》2012,48(1):65-71
We consider multidimensional integral operators with homogeneous-difference kernels acting in L
p
-spaces. For such operators, we prove a boundedness theorem and establish an invertibility criterion. 相似文献
17.
Shuichi Sato 《Integral Equations and Operator Theory》2008,62(3):429-440
We prove certain L
p
-estimates for Littlewood-Paley functions arising from rough kernels. The estimates are useful for extrapolation to prove
L
p
-boundedness of the Littlewood-Paley functions under a sharp kernel condition.
相似文献
18.
Dan Timotin 《Integral Equations and Operator Theory》1986,9(2):295-304
For a certain class of operators defined by integral kernels, a necessary and sufficient condition is given for the belonging to the Schatten-von Neumann idealsC
P. The operators considered generalize the classical Hankel operators; the results thus extend Peller's characterization of the Hankel operators in a classC
P. 相似文献
19.
Boundedness of commutators on homogeneous Herz spaces 总被引:9,自引:0,他引:9
The boundedness on homogeneous Herz spaces is established for a large class of linear commutators generated by BMO(R
n
) functions and linear operators of rough kernels which include the Calderón-Zygmund operators and the Ricci-Stein oRfiUatory
singular integrals with rough kernels.
Project supponed in pan by the National h’atural Science Foundation of China (Grant No. 19131080) and the NEDF of China. 相似文献
20.
Augustin Banyaga 《Annals of Global Analysis and Geometry》1996,14(4):427-441
We exhibit new invariants of the contact structure E(), the contact flow F
and the transverse symplectic geometry of a contact manifold (M, ). The invariant of contact structures generalizes to transversally oriented foliations. We focus on the particular cases of orientations of smooth manifolds and transverse orientations of foliations. We define the transverse Calabi invariants and determine their kernels.Supported in part by NSF grants DMS 90-01861 and DMS 94-03196. 相似文献