共查询到20条相似文献,搜索用时 31 毫秒
1.
Aldo Portela 《Bulletin of the Brazilian Mathematical Society》2007,38(4):623-633
Although every Cantor subset of the circle (S1) is the minimal set of some homeomorphism of S1, not every such set is minimal for a C1 diffeomorphism of S1. In this work, we construct new examples of Cantor sets in S1 that are not minimal for any C1-diffeomorphim of S1. 相似文献
2.
Jia Gao 《高校应用数学学报(英文版)》2007,22(2):174-180
Let L^p(Ω, H^n) indicate the L^P-space of the maps for Heisenberg group target. In this paper some new properties are obtained for the space L^p(Ω, H^n) 相似文献
3.
J. C. Gómez-Larrañaga F. González-Acuña Wolfgang Heil 《Mathematische Zeitschrift》2008,259(2):419-432
A closed topological n-manifold M
n
is of S
1-category 2 if it can be covered by two open subsets W
1,W
2 such that the inclusions W
i
→ M
n
factor homotopically through maps W
i
→ S
1 → M
n
. We show that the fundamental group of such an n-manifold is a cyclic group or a free product of two cyclic groups with nontrivial amalgamation. In particular, if n = 3, the fundamental group is cyclic.
相似文献
4.
Piotr Kalemba Szymon Plewik Anna Wojciechowska 《Central European Journal of Mathematics》2008,6(2):218-227
The σ-ideal (v
0) is associated with the Silver forcing, see [5]. Also, it constitutes the family of all completely doughnut null sets, see
[9]. We introduce segment topologies to state some resemblances of (v
0) to the family of Ramsey null sets. To describe add(v
0) we adopt a proof of Base Matrix Lemma. Consistent results are stated, too. Halbeisen’s conjecture cov(v
0) = add(v
0) is confirmed under the hypothesis t = min{cf(c), r}. The hypothesis cov(v
0) = ω
1 implies that (v
0) has the ideal type (c, ω
1, c).
相似文献
5.
In the present paper we consider a von Neumann algebra M with a faithful normal semi-finite trace τ, and {α
t
}, a strongly continuous extension to L
p
(M, τ) of a semigroup of absolute contractions on L
1(M, τ). By means of a non-commutative Banach Principle we prove for a Besicovitch function b and x ∊ L
p
(M, τ), that the averages 1/T ∫0
T
b(t)α
t
(x)dt converge bilateral almost uniformly in L
p
(M, τ) as T → 0.
Communicated by Dénes Petz 相似文献
6.
Bao Qin Li 《Mathematische Zeitschrift》2008,258(4):763-771
We show that meromorphic solutions f, g of f
2 + g
2 = 1 in C2 must be constant, if f
z2 and g
z1 have the same zeros (counting multiplicities). We also apply the result to characterize meromorphic solutions of certain
nonlinear partial differential equations. 相似文献
7.
QiaoLingXIA YiBingSHEN 《数学学报(英文版)》2004,20(6):1029-1046
In this paper, we reformulate the Euler-Lagrange equations of Willmore surfaces in S^n as the flatness of a family of certain loop algebra-valued 1-forms. Therefore we can give the Weierstrass type representation of conformal Willmore surfaces. We also discuss the relations between conformal Willmore surfaces in S^n and minimal surfaces in constant curvature spaces S^n, R^n, H^n, and prove that some special Willmore surfaces can be derived from minimal surfaces in S^n, R^n, H^n. 相似文献
8.
J. Wei recently proposed a concept of *
s
-modules which is another generalization of *-modules besides *
n
-modules [J. Algebra, 2005, 291: 312–324]. In this paper, we consider the co-*
s
-modules and give some characterizations and properties. It is found that the class of co-*
s
-modules contains co-selfsmall injective cogenerators. The relations between co-*
s
-modules and co-*
n
-modules are also considered. 相似文献
9.
L
p
approximation capability of radial basis function (RBF) neural networks is investigated. If g: R
+1 → R
1 and ∈ L
loc
p
(R
n
) with 1 ≤ p < ∞, then the RBF neural networks with g as the activation function can approximate any given function in L
p
(K) with any accuracy for any compact set K in R
n
, if and only if g(x) is not an even polynomial.
Partly supported by the National Natural Science Foundation of China (10471017) 相似文献
10.
ZhangJianfeng 《高校应用数学学报(英文版)》2005,20(2):183-196
Let M^n be a closed spacelike submanifold isometrically immersed in de Sitter space Sp^(n p)(c), Denote by R,H and S the normalized scalar curvature,the mean curvature and the square of the length of the second fundamental form of M^n ,respectively. Suppose R is constant and R≤c. The pinching problem on S is studied and a rigidity theorem for M^n immersed in Sp^(n p)(c) with parallel normalized mean curvature vector field is proved. When n≥3, the pinching constant is the best. Thus, the mistake of the paper “Space-like hypersurfaces in de Sitter space with constant scalar curvature”(see Manus Math, 1998,95 :499-505) is corrected. Moreover,the reduction of the codimension when M^n is a complete submanifold in Sp^(n p)(c) with parallel normalized mean curvature vector field is investigated. 相似文献
11.
T. S. Kopaliani 《Ukrainian Mathematical Journal》2008,60(12):2006-2014
We point out that if the Hardy–Littlewood maximal operator is bounded on the space L
p(t)(ℝ), 1 < a ≤ p(t) ≤ b < ∞, t ∈ ℝ, then the well-known characterization of the spaces L
p
(ℝ), 1 < p < ∞, by the Littlewood–Paley theory extends to the space L
p(t)(ℝ). We show that, for n > 1 , the Littlewood–Paley operator is bounded on L
p(t) (ℝ
n
), 1 < a ≤ p(t) ≤ b < ∞, t ∈ ℝ
n
, if and only if p(t) = const.
Published in Ukrains’kyi Matematychnyi Zhurnal, Vol. 60, No. 12, pp. 1709–1715, December, 2008. 相似文献
12.
Zhijian Qiu 《Integral Equations and Operator Theory》2007,59(2):223-244
Let K be a compact subset in the complex plane and let A(K) be the uniform closure of the functions continuous on K and analytic on K°. Let μ be a positive finite measure with its support contained in K. For 1 ≤ q < ∞, let Aq(K, μ) denote the closure of A(K) in Lq(μ). The aim of this work is to study the structure of the space Aq(K, μ). We seek a necessary and sufficient condition on K so that a Thomson-type structure theorem for Aq(K, μ) can be established. Our theorem deduces J. Thomson’s structure theorem for Pq(μ), the closure of polynomials in Lq(μ), as the special case when K is a closed disk containing the support of μ. 相似文献
13.
Michael J. Puls 《Archiv der Mathematik》2007,88(6):500-506
Let p be a real number greater than one. In this paper we study the vanishing and nonvanishing of the first L
p
-cohomology space of some groups that have one end. We also make a connection between the first L
p
-cohomolgy space and the Floyd boundary of the Cayley graph of a group. We apply the result about Floyd boundaries to show
that there exists a real number p such that the first L
p
-cohomology space of a nonelementary hyperbolic group does not vanish.
Received: 4 August 2006 Revised: 2 November 2006 相似文献
14.
Functions whose translates span L
p
(R) are called L
p-cyclic functions. For a fixed
p \memb [1, \infty], we construct Schwartz-class functions which are L
r
-cyclic for r > p and not L
r
-
cyclic for r \le p. We then construct Schwartz-class functions which are L
r
-cyclic for r \ge p and
not L
r
-cyclic for r < p. The constructions differ for p \memb (1, 2) and p > 2. 相似文献
15.
Regina Rotman 《Mathematische Zeitschrift》2007,257(2):427-437
Let M
n
be a closed 2-connected Riemannian manifold, such that π3(M
n
) ≠ { 0 }. In this paper we prove that either there exists a periodic geodesic on M
n
of length ≤ 6d, where d is the diameter of M
n
, or at each point p ∈ M
n
there exists a geodesic loop of length ≤ 2d. 相似文献
16.
We show that for each positive integerk there is ak×k matrixB with ±1 entries such that puttingE to be the span of the rows of thek×2k matrix [√kI
k,B], thenE,E
⊥ is a Kashin splitting: TheL
1
2k
and theL
2
2k
are universally equivalent on bothE andE
⊥. Moreover, the probability that a random ±1 matrix satisfies the above is exponentially close to 1.
Supported by the Israel Science Foundation. 相似文献
17.
This paper gets some necessary conditions for the existence of some kinds of clear 4^m2^n compromise plans which allow estimation of all main effects and some specified two-factor interactions without assuming the remaining two-factor interactions being negligible. Some methods for constructing clear 4^m2^n compromise plans are introduced. 相似文献
18.
Humio Ichimura 《Archiv der Mathematik》2011,96(6):555-563
Let p be an odd prime number, and pn0{p^{n_0}} the highest power of p dividing 2
p−1 − 1. Let Kn=Q(zpn+1){K_n={\bf Q}(\zeta_{p^{n+1}})} and Ln,j=Kn+(z2j+2){L_{n,j}=K_n^+(\zeta_{2^{j+2}})} for j ≥ 0. Let hn*{h_n^*} be the relative class number of K
n
, and h
n,j
the class number of L
n,j
, respectively. Let n be an integer with n ≥ n
0. We prove that if the ratio hn*/hn-1*{h_n^*/h_{n-1}^*} is odd, then h
n,j
/h
n−1,j
is odd for any j ≥ 0. 相似文献
19.
For any complex valued L
p
-function b(x), 2 ≤ p < ∞, or L
∞-function with the norm ‖b↾L
∞‖ < 1, the spectrum of a perturbed harmonic oscillator operator L = −d
2/dx
2 + x
2 + b(x) in L
2(ℝ1) is discrete and eventually simple. Its SEAF (system of eigen- and associated functions) is an unconditional basis in L
2(ℝ). 相似文献
20.
As the main result, we show that if G is a finite group such that Γ(G) = Γ(2
F
4(q)), where q = 22m+1 for some m ≧ 1, then G has a unique nonabelian composition factor isomorphic to 2
F
4(q). We also show that if G is a finite group satisfying |G| =|2
F
4(q)| and Γ(G) = Γ(2
F
4(q)), then G ≅ 2
F
4(q). As a consequence of our result we give a new proof for a conjecture of W. Shi and J. Bi for 2
F
4(q).
The third author was supported in part by a grant from IPM (No. 87200022). 相似文献