共查询到20条相似文献，搜索用时 31 毫秒
1.
Abstract. Weakly left ample semigroups are a class of semigroups that are (2,1) -subalgebras of semigroups of partial transformations, where the unary operation takes a transformation α to the identity map in the domain of α . It is known that there is a class of proper weakly left ample semigroups whose structure is determined by unipotent monoids acting on semilattices or categories. In
this paper we show that for every finite weakly left ample semigroup S , there is a finite proper weakly left ample semigroup
and an onto morphism from
to S which separates idempotents. In fact,
is actually a (2,1) -subalgebra of a symmetric inverse semigroup, that is, it is a left ample semigroup (formerly, left type A). 相似文献
2.
Micciancio 《Discrete and Computational Geometry》2003,29(1):133-138
Abstract. We prove that the best way to reduce the volume of the n -dimensional unit cube by a linear transformation that maps each of the main vertices
to a point within distance ɛ <
from
is to shorten all edges by a factor (1-ɛ) . In particular, the minimal volume of such an almost cubic parallelepiped is (1-ɛ)
n
. This problem naturally arises in the construction of lattice-based one-way functions with worst-case/ average-case connection. 相似文献
3.
周泽华 《中国科学A辑(英文版)》2003,46(1):33-38
Let Un be the unit polydisc of Cn and φ= (φ1,...,φn? a holomorphic self-map of Un. Let 0≤α< 1. This paper shows that the composition operator Cφ, is bounded on the Lipschitz space Lipa(Un) if and only if there exists M > 0 such thatfor z∈Un. Moreover Cφ is compact on Lipa(Un) if and only if Cφ is bounded on Lipa(Un) and for every ε > 0, there exists a δ > 0 such that whenever dist(φ(z),σUn) <δ 相似文献
4.
In this paper we investigate the spectral exponent, i.e. logarithm of the spectral radius of operators having the form
and acting in spaces Lp(X, μ), where X is a compact topological space, φk∈C(X), φ = (φk)k=1N∈C(X)N, and
are linear positive operators (Ukf≥ 0 for f≥ 0). We consider the spectral exponent ln r(Aφ) as a functional depending on vector-function φ. We prove that ln r(Aφ) is continuous and on a certain subspace
of C(X)N is also convex. This yields that the spectral exponent is the Fenchel-Legendre transform of a convex functional
defined on a set
of continuous linear positive and normalized functionals on the subspace
of coefficients φ that is
相似文献
5.
Compact composition operators on the Bloch space in polydiscs 总被引：1，自引：0，他引：1
Let Un be the unit polydisc of ℂn and φ=(φ1, ⋯, φ
n
) a holomorphic self-map of Un. As the main result of the paper, it shows that the composition operator C is compact on the Bloch space β(Un) if and only if for every ε > 0, there exists a δ > 0, such that
whenever dist(φ(z), ∂U
n
)<δ. 相似文献
6.
Equations with two time scales (refinement equations or dilation equations) are central to wavelet theory. Several applications
also include an inhomogeneous forcing term F(t). We develop here a part of the existence theory for the inhomogeneous refinement
equation
where a (k) is a finite sequence and F is a compactly supported distribution on ℝ.
The existence of compactly supported distributional solutions to an inhomogeneous refinement equation is characterized in
terms of conditions on the pair (a, F).
To have Lp solutions from F ∈ Lp(ℝ), we construct by the cascade algorithm a sequence of functions φ0 ∈ Lp(ℝ) from a compactly supported initial function ℝ as
A necessary and sufficient condition for the sequence {φn} to converge in Lp(ℝ)(1 ≤ p ≤ ∞) is given by the p-norm joint spectral radius of two matrices derived from the mask a. A convexity property
of the p-norm joint spectral radius (1 ≤ p ≤ ∞) is presented.
Finally, the general theory is applied to some examples and multiple refinable functions.
Acknowledgements and Notes. Research supported in part by Research Grants Council and City University of Hong Kong under Grants #9040281, 9030562, 7000741. 相似文献
7.
Witold Bednorz 《Journal of Theoretical Probability》2007,20(4):917-934
For a Young function φ and a Borel probability measure m on a compact metric space (T,d) the minorizing metric is defined by
In the paper we extend the result of Kwapien and Rosinski (Progr. Probab. 58, 155–163, 2004) relaxing the conditions on φ under which there exists a constant K such that
for each separable process X(t), t∈T which satisfies
. In the case of φ
p
(x)≡x
p
, p≥1 we obtain the somewhat weaker results.
Partially supported by the Funds of Grant MENiN 1 P03A 01229. 相似文献
8.
M. J. Appel 《Journal of Theoretical Probability》2002,15(1):153-159
Birkhoff's well-known ergodic theorem states that the simple averages of a sequence of real (integrable) function values on successive iterates of a measure-preserving mapping T converge a.s. to the conditional expected value of the function conditioned on the invariant sigma-field. If the mapping is in addition ergodic, then the limit is simply the unconditional expected value:
In this article, we discuss the analogous result for sequences of partial maxima: given a measurable f, if T is measure-preserving and ergodic then
Series criteria are provided which characterize the a.s. maximal and minimal growth rates of the sequence of partial maxima. 相似文献
9.
Summary. We prove a functional central limit theorem for stationary random sequences given by the transformations
on the two-dimensional torus. This result is based on a functional central limit theorem for ergodic stationary martingale
differences with values in a separable Hilbert space of square integrable functions.
Received: 11 March 1997 / In revised form: 1 December 1997This research was supported by the Deutsche Forschungsgemeinschaft
and the Russian Foundation for Basic Research, grant 96-01-00096. The second author was also partially supported by INTAS,
grant 94-4194. 相似文献
10.
Suppose denote the ergodic averages for the natural numbers . Let denote the corresponding maximal function and let for . We show that for if there exists such that then there exists such that . Similar weak (1,1) inequalities follow for V
q
when you know them for M too also with q > 1. We also show this fails completely if q= 1. We also show that for certain polynomial like and random sequences , if
and
is of exponential growth then
for a certain positive constant C.
(Received 11 February 1998; in revised form 10 December 1998) 相似文献
11.
For almost all p-restricted irreducible representations of the group An(K) in characteristic p > 0 with highest weights large enough with respect to p, the Jordan block structure of the images
of small quadratic unipotent elements in these representations is determined. It is proved that if φ is an irreducible p-restricted
representation of An(K) with highest weight
, not too few of the coefficients mi are less than p − 1, and n is large enough with respect to the codimension of the fixed subspace of an element z under consideration,
then φ(z) has blocks of all sizes from 1 to p. Bibliography: 15 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 343, 2007, pp. 84–120. 相似文献
12.
There are reverse inequalities for square functions of differences arising in ergodic theory and differentiation of functions.
For example, it is shown that if An is the usual average in ergodic theory, and (nk∶k=1,2,3,...) is an increasing lacunary sequence with no non-trivial common divisor, then one has for any p, 1<p<∞, there
is a constant Cp such that for all f∃ Lp(X),
. 相似文献
13.
Inho Kim 《manuscripta mathematica》1998,97(3):343-352
We prove an optimal relative isoperimetric inequality
for a 2-dimensional minimal surface in the n-dimensional space form of nonpositive constant curvature κ under the assumptions that lies in the exterior of a convex domain and contains a subset Γ which is contained in
and along which meets perpendicularly and that is connected, or more generally radially-connected from a point in Γ. Also we obtain an optimal version of linear isoperimetric
inequalities for minimal submanifolds in a simply connected Riemannian manifolds with sectional curvatures bounded above by
a nonpositive number. Moreover, we show the monotonicity property for the volume of a geodesic ball in such minimal submanifolds.
We emphasize that in all the results of this paper minimal submanifolds need not be area minimizing or even stable.
Received: 7 October 1997 / Revised version: 28 April 1998 相似文献
14.
We study the Riemann-Hilbert problem of finding φ, ψ ∈ Hp such that their nontangential boundary values satisfy the equation
where
is a given 2π-periodic continuous function. We prove the nonexistence of nontrivial solutions for a wide class of continuous
vanishing complex-valued coefficients a. 相似文献
15.
F. Mukhamedov 《Functional Analysis and Its Applications》2007,41(4):311-313
We consider strictly ergodic and strictly weakly mixing C*-dynamical cystems. We establish that a system is strictly weakly mixing if and only if its tensor product is strictly ergodic and strictly weakly mixing. We also investigate some weighted uniform ergodic theorem with respect to S-Besicovitch sequences for strictly weakly mixing dynamical systems. 相似文献
16.
It is well known that the recurrence relations
are periodic, in the sense that they define periodic sequences for all choices of the initial data, and lead to sequences
with periods 2, 5 and 8, respectively. In this paper we determine all periodic recursions of the form
where are complex numbers, are non-zero and . We find that, apart from the three recursions listed above, only
lead to periodic sequences (with periods 6 and 8). The non-periodicity of (R) when (or and ) depends on the connection between (R) and the recurrence relations
and
We investigate these recursions together with the related
Each of (A), (B), and (C) leads to periodic sequences if k = 1 (with periods 6, 5, and 9, respectively). Also, for k = 2, (B) leads to periodicity with period 8. However, no other cases give rise to periodicity. We also prove that every real
sequence satisfying any of (A), (B), and (C) must be bounded. As a consequence, we find that for an arbitrary k, every rational sequence satisfying any of (A), (B), and (C) must be periodic.
(Received 27 June 2000; in revised form 5 January 2001) 相似文献
17.
E.G. Coffman Jr. George S. Lueker Joel Spencer Peter M. Winkler 《Probability Theory and Related Fields》2001,120(4):585-599
A random rectangle is the product of two independent random intervals, each being the interval between two random points
drawn independently and uniformly from [0,1]. We prove that te number C
n
of items in a maximum cardinality disjoint subset of n random rectangles satisfies
where K is an absolute constant. Although tight bounds for the problem generalized to d > 2 dimensions remain an open problem, we are able to show that, for some absolute constat K,
Finally, for a certain distribution of random cubes we show that for some absolute constant K, the number Q
n
of items in a maximum cardinality disjoint subset of the cubes satisies
Received: 1 September 1999 / Revised version: 3 November 2000 / Published online: 14 June 2001 相似文献
18.
XinPingWANG 《数学学报(英文版)》2003,19(4):765-782
In this paper,we are concerned with the boundedness of all the solutions of the equation x″ ax^ -bx- Ф(x)=p(t),where p(t) is a smooth 2π-periodic function,a and b are positive constants,and the perturbation Ф(x) is bounded. 相似文献
19.
I. Assani 《Israel Journal of Mathematics》1998,103(1):111-124
We prove the following: Let (X, β, μ,T) be a weakly mixing dynamical system such that the restriction ofT to its Pinsker algebra has singular spectrum, then for all positive integersH, for allf
i ∈L
∞, 1≤i≤H, the averages
.
Research supported in part by NSF Grant #DMS 9305754 相似文献
20.
We study a quasilinear elliptic problem
with nonhomogeneous principal part φ. Under the hypothesis f(x,t)= o(φ(t)t) at t= 0 and ∞, the existence of multiple positive solutions is proved by using the variational arguments in the Orlicz–Sobolev
spaces.
Mathematics Subject Classification (2000) 35J20; 35J25; 35J70; 47J10; 47J30 相似文献