共查询到20条相似文献,搜索用时 31 毫秒
1.
Basudeb Dhara 《Rendiconti del Circolo Matematico di Palermo》2008,57(3):401-410
Let R be a prime ring of char R ≠ = 2 with center Z(R) and with extended centroid C, d a nonzero derivation of R and f(x
1, ..., x
n
) a nonzero multilinear polynomial over C. Suppose that x
s
d(x)x
t
∈ Z(R) for all x ∈ {d(f(x
1, ..., x
n
))|x
1, ..., x
n
∈ ρ}, where ρ is a nonzero right ideal of R and s ≥ 0, t ≥ 0 are fixed integers. If d(ρ)ρ ≠ = 0, then ρ
C = eRC for some idempotent e in the socle of RC and f(x
1, ..., x
n
)
N
is central-valued in eRCe, where N = s + t + 1.
相似文献
2.
Rong-mao ZHANG & Zheng-yan LIN Department of Mathematics Zhejiang University Hangzhou China 《中国科学A辑(英文版)》2007,50(1):35-46
Let {W(t),t∈R}, {B(t),t∈R } be two independent Brownian motions on R with W(0) = B(0) = 0. In this paper, we shall consider the exact Hausdorff measures for the image and graph sets of the d-dimensional iterated Brownian motion X(t), where X(t) = (Xi(t),... ,Xd(t)) and X1(t),... ,Xd(t) are d independent copies of Y(t) = W(B(t)). In particular, for any Borel set Q (?) (0,∞), the exact Hausdorff measures of the image X(Q) = {X(t) : t∈Q} and the graph GrX(Q) = {(t, X(t)) :t∈Q}are established. 相似文献
3.
Н. Н. Пустовойтов 《Analysis Mathematica》1994,20(1):35-48
In this paper the author studies classesH
q
of periodic functions of several variables whose mixed moduli of continuity do not exceed a given modulus of continuity (t
1 ...,t
d
). Necessary and sufficient conditions of belonging of a functionf(x
1, ...,x
d
) to the classH
q
are considered (Theorem 1). These necessary and sufficient conditions are proved under some additional assumptions on (t
1, ...,t
d
). It is shown that additional assumptions cannot be omitted (Theorem 3). Besides, the estimates of best approximations of classesH
q
with some special (t
1, ...,t
d
) are given (Theorems 4 and 5). 相似文献
4.
Let {B
1
d
(t)} and {B
d
2(t)} be independent Brownian motions in R
d
starting from 0 and nx respectively, and let w
d
i
(a,b) ={xR
d
: B
d
i
(t)=x for some t(a,b)}, i=1,2. Asymptotic expressions as n for the probability of dist(w
d
1(n
2
t
1, n
2
t
2), w
2
d
(0,n
2
t
3))1 with d4, respectively for the probability of dist(w
1
4(n
2
t
1,n
2
t
2),w
2
4(0,n
2
t
3))1 are obtained. As an application, an improvement of a result due to M. Aizenman concerning the intersections of Wiener sausages in R
4 is presented. 相似文献
5.
Dong Sheng WU Yi Min XIAO 《数学学报(英文版)》2007,23(4):613-622
Let B^α = {B^α(t),t E R^N} be an (N,d)-fractional Brownian motion with Hurst index α∈ (0, 1). By applying the strong local nondeterminism of B^α, we prove certain forms of uniform Hausdorff dimension results for the images of B^α when N 〉 αd. Our results extend those of Kaufman for one-dimensional Brownian motion. 相似文献
6.
R. Norvaiša 《Lithuanian Mathematical Journal》2008,48(4):418-426
Let B
H,K
= {B
H,K
(t)}
t⩾0 be a bifractional Brownian motion with parameters H ∈ (0, 1) and K ∈ (0, 1]. For a function Φ: [0, ∞) → [0, ∞) and for a partition κ = {t
i
}n
i=0 of an interval [0, T] with T > 0, let {ie418-01}. We prove that, for a suitable Φ depending on H and K, {ie418-02} almost surely.
The research was partially supported by the Lithuanian State Science and Studies Foundation, grant No. T-16/08 相似文献
7.
Y. -K. Choi 《Acta Mathematica Hungarica》2009,123(4):331-355
This paper establishes the general moduli of continuity for l
∞-valued Gaussian random fields {X(t):= (X
1(t),X
2(t), h.), t ∈ [0, ∞)
N
} indexed by the N-dimensional parameter t:= (t
1,…,t
N
), under the explicit condition yielding that the covariance function of distinct increments of X
k
(t) for fixed k ≧ 1 is positive or nonpositive.
Supported by KOSEF-R01-2008-000-11418-0. 相似文献
8.
Ji-pu Ma Tseng Yaun Rong Functional Analysis Research Center Harbin Normal University Harbin China 《中国科学A辑(英文版)》2007,50(9):1233-1239
Let E, F be two Banach spaces, and B(E, F), Φ(E, F), SΦ(E, F) and R(E,F) be the bounded linear, Fredholm, semi-Frdholm and finite rank operators from E into F, respectively. In this paper, using the continuity characteristics of generalized inverses of operators under small perturbations, we prove the following result Let ∑ be any one of the following sets {T ∈ Φ(E, F) IndexT =const, and dim N(T) = const.}, {T ∈ SΦ(E, F) either dim N(T) = const. < ∞ or codim R(T) = const.< ∞} and {T ∈ R(E, F) RankT =const.<∞}. Then ∑ is a smooth submanifold of B(E, F) with the tangent space TA∑ = {B ∈ B(E,F) BN(A) (∪) R(A)} for any A ∈ ∑. The result is available for the further application to Thom's famous results on the transversility and the study of the infinite dimensional geometry. 相似文献
9.
For a stochastically continuous stochastic process with independent increments overD[0,T], letN(t,ε) be the number of smaple function jumps that occur in the interval [0,t] of sizes less than −ε or greater than ε, where ε>0. LetM(t,ε)=EN(t,ε), and assumeM(t,0+)=∞ for 0<t≦T. If limε
↓0(M(t,ε)/M(T,ε)) exists and is positive for eacht∈(0,T], then limε
↓0(N(t,ε)/M(T,ε)) for allt∈(0,T] with probability one.
The research of Howard G. Tucker was supported in part by the National Science Foundation, Grant No. MCS76-03591A01. 相似文献
10.
Z. Shi 《Journal of Theoretical Probability》1996,9(4):915-929
LetR be the radial part of ad-dimensional Wiener process, starting from 0. In this paper, small ball probabilities are evaluated for sup0<11(t
–p
R(t)) and sup
t
0(e
–1
R(t)), withp[0, 1/2]. Chung's law of the iterated logarithm is established for the supremum of the local times of a two-dimensional Bessel process. 相似文献
11.
Loukas GRAFAKOS 《中国科学A辑(英文版)》2008,51(12):2253-2284
Let X be an RD-space, i.e., a space of homogeneous type in the sense of Coifman and Weiss, which has the reverse doubling property. Assume that X has a dimension n. For α∈ (0, ∞) denote by Hαp(X ), Hdp(X ), and H?,p(X ) the corresponding Hardy spaces on X defined by the nontangential maximal function, the dyadic maximal function and the grand maximal function, respectively. Using a new inhomogeneous Calder′on reproducing formula, it is shown that all these Hardy spaces coincide with Lp(X ) when p ∈ (1, ∞] a... 相似文献
12.
《随机分析与应用》2013,31(4):815-837
We find the chaos expansion of local time ? T (H)(x,·) of fractional Brownian motion with Hurst coefficient H∈(0,1) at a point x∈R d . As an application we show that when H 0 d<1 then ? T (H)(x,·)∈L 2(μ). Here μ denotes the probability law of B (H) and H 0=max{H 1,…,H d }. In particular, we show that when d=1 then ? T (H)(x,·)∈L 2(μ) for all H∈(0,1). 相似文献
13.
Let X={X(t),t∈ℝ
N
} be a Gaussian random field with values in ℝ
d
defined by
X(t) = (X1(t), ?, Xd(t)), t ? \mathbbRN,X(t) = (X_1(t), \ldots, X_d(t)),\quad t \in {\mathbb{R}}^N, 相似文献
14.
Let X(t) be an N parameter generalized Lévy sheet taking values in ℝd with a lower index α, ℜ = {(s, t] = ∏
i=1
N
(s
i, t
i], s
i < t
i}, E(x, Q) = {t ∈ Q: X(t) = x}, Q ∈ ℜ be the level set of X at x and X(Q) = {x: ∃t ∈ Q such that X(t) = x} be the image of X on Q. In this paper, the problems of the existence and increment size of the local times for X(t) are studied. In addition, the Hausdorff dimension of E(x, Q) and the upper bound of a uniform dimension for X(Q) are also established. 相似文献
15.
Philippe et al. [9], [10] introduced two distinct time-varying mutually invertible fractionally integrated filters A(d), B(d) depending on an arbitrary sequence d = (d
t
)
t∈ℤ of real numbers; if the parameter sequence is constant d
t
≡ d, then both filters A(d) and B(d) reduce to the usual fractional integration operator (1 − L)−d
. They also studied partial sums limits of filtered white noise nonstationary processes A(d)ε
t
and B(d)ε
t
for certain classes of deterministic sequences d. The present paper discusses the randomly fractionally integrated stationary processes X
t
A
= A(d)ε
t
and X
t
B
= B(d)ε
t
by assuming that d = (d
t
, t ∈ ℤ) is a random iid sequence, independent of the noise (ε
t
). In the case where the mean
, we show that large sample properties of X
A
and X
B
are similar to FARIMA(0,
, 0) process; in particular, their partial sums converge to a fractional Brownian motion with parameter
. The most technical part of the paper is the study and characterization of limit distributions of partial sums for nonlinear
functions h(X
t
A
) of a randomly fractionally integrated process X
t
A
with Gaussian noise. We prove that the limit distribution of those sums is determined by a conditional Hermite rank of h. For the special case of a constant deterministic sequence d
t
, this reduces to the standard Hermite rank used in Dobrushin and Major [2].
Published in Lietuvos Matematikos Rinkinys, Vol. 47, No. 1, pp. 3–28, January–March, 2007. 相似文献
16.
Fu Bao XI 《数学学报(英文版)》2005,21(3):457-464
In this paper, we consider the Markov process (X^∈(t), Z^∈(t)) corresponding to a weakly coupled elliptic PDE system with a small parameter ∈ 〉 0. We first prove that (X^∈(t), Z^∈(t)) has the Feller continuity by the coupling method, and then prove that (X^∈(t), Z^∈(t)) has an invariant measure μ^∈(·) by the Foster-Lyapunov inequality. Finally, we establish a large deviations principle for μ^∈(·) as the small parameter e tends to zero. 相似文献
17.
Yu. A. Farkov 《Mathematical Notes》2000,68(2):248-254
Suppose thatB
R
d
is a ball of radiusR in ℂ
d
and σ is the standard measure on the unit sphere in ℂ
d
. ForR>1, 1≤p≤∞, and for the natural numbersl, d, byH
R
0
(l, p, d) we denote the class of functionsf holomorphic inB
R
d
and such that in the homogeneous polynomial expansion of the firstl summands the zero and radial derivatives of orderl belong to the closed unit ball of the Hardy spaceH
p
(B
R
d
). In this paper an asymptotic formula for the ε-entropy of the classH
R
0
(l, p, d) in the spacesL
p
(σ), 1≤p<∞, and
is obtained.
Translated fromMatematicheskie Zametki, Vol. 68, No. 2, pp. 286–293, August, 2000. 相似文献
18.
Mario Wschebor 《Probability Theory and Related Fields》1982,60(3):393-401
Summary Let {x(t): tR
d} a stochastic process with parameter in R
d, and u a fixed real number. Denote by C
u, Au, Bu respectively the random sets {t: x(t)= u}, {t: x(t)}, {t: x(t)>u}. The paper contains two main results for processes with continuously differentiable paths plus some additional requirements: First, a formula for the expectation of Q
T(Au) and Q
T(Bu), where for a given bounded open set T in R
d, QT(B) denotes the perimeter of B relative to T and second, sufficient conditions on the process, so that it does not have local extrema on the barrier u. The second result can also be used to interpret the first in terms of C
u. 相似文献
19.
Zong-mao Cheng Xiu-yun Wang Zheng-yan Lin 《应用数学学报(英文版)》2006,22(1):81-90
In this paper, we introduce a class of Gaussian processes Y={Y(t):t∈R^N},the so called hifractional Brownian motion with the indcxes H=(H1,…,HN)and α. We consider the (N, d, H, α) Gaussian random field x(t) = (x1 (t),..., xd(t)),where X1 (t),…, Xd(t) are independent copies of Y(t), At first we show the existence and join continuity of the local times of X = {X(t), t ∈ R+^N}, then we consider the HSlder conditions for the local times. 相似文献
20.
The Blow-up Locus of Heat Flows for Harmonic Maps 总被引:5,自引:0,他引:5
Abstract
Let M and N be two compact Riemannian manifolds. Let u
k
(x, t) be a sequence of strong stationary weak heat flows from M×R
+ to N with bounded energies. Assume that u
k→u weakly in H
1, 2(M×R
+, N) and that Σt is the blow-up set for a fixed t > 0. In this paper we first prove Σt is an H
m−2-rectifiable set for almost all t∈R
+. And then we prove two blow-up formulas for the blow-up set and the limiting map. From the formulas, we can see that if the
limiting map u is also a strong stationary weak heat flow, Σt is a distance solution of the (m− 2)-dimensional mean curvature flow [1]. If a smooth heat flow blows-up at a finite time, we derive a tangent map or a weakly
quasi-harmonic sphere and a blow-up set ∪t<0Σt× {t}. We prove the blow-up map is stationary if and only if the blow-up locus is a Brakke motion.
This work is supported by NSF grant 相似文献
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