共查询到20条相似文献,搜索用时 31 毫秒
1.
D. V. Zakharov 《Functional Analysis and Its Applications》2011,45(1):25-32
Using an integrable discrete Dirac operator, we construct a discrete version of the Weierstrass representation for hyperbolic
surfaces parameterized along isotropic directions in ℝ2,1, ℝ3,1, and ℝ2,2. The corresponding discrete surfaces have isotropic edges. We show that any discrete surface satisfying a general monotonicity
condition and having isotropic edges admits such a representation. 相似文献
2.
We define the notion of projective multiresolution analyses, for which, by definition,
the initial space corresponds to a finitely generated projective module over the algebra
C(Tn) of continuous complex-valued functions on an n-torus. The case of ordinary multi-wavelets
is that in which the projective module is actually free. We discuss the properties of projective
multiresolution analyses, including the frames which they provide for L2(n). Then we show how
to construct examples for the case of any diagonal 2 × 2 dilation matrix with integer entries, with
initial module specified to be any fixed finitely generated projective C(T2)-module. We compute
the isomorphism classes of the corresponding wavelet modules. 相似文献
3.
Emily J. King Maria A. Skopina 《P-Adic Numbers, Ultrametric Analysis, and Applications》2010,2(3):222-231
With an eye on applications in quantum mechanics and other areas of science, much work has been done to generalize traditional
analytic methods to p-adic systems. In 2002 the first paper on p-adic wavelets was published. Since then p-adic wavelet sets, multiresolution analyses, and wavelet frames have all been introduced. However, so far all constructions
have involved dilations by p. This paper presents the first construction of a p-adic wavelet system with a more general matrix dilation, laying the foundation for further work in this direction. 相似文献
4.
David Kalaj 《Israel Journal of Mathematics》2005,150(1):241-251
We give the new inequality related to the J. C. C. Nitsche conjecture (see [6]). Moreover, we consider the two- and three-dimensional case. LetA(r, 1)={z:r<|z|<1}. Nitsche's conjecture states that if there exists a univalent harmonic mapping from an annulusA(r, 1), to an annulusA(s, 1), thens is at most 2r/(r 2+1).Lyzzaik's result states thats<t wheret is the length of the Grötzsch's ring domain associated withA(r, 1) (see [5]). Weitsman's result states thats≤1/(1+1/2(r logr)2) (see [8]).Our result for two-dimensional space states thats≤1/(1+1/2 log2 r) which improves Weitsman's bound for allr, and Lyzzaik's bound forr close to 1. For three-dimensional space the result states thats≤1/(r?logr). 相似文献
6.
Yemon Choi 《Semigroup Forum》2007,75(2):253-271
We show that if L is a semilattice then the ℓ1-convolution algebra of L is biflat precisely when L is "uniformly locally finite". Our proof technique shows in passing
that if this convolution algebra is biflat then it is isomorphic as a Banach algebra to the Banach space ℓ1(L) equipped with pointwise multiplication. At the end we sketch how these techniques may be extended to prove an analogous
characterisation of biflatness for Clifford semigroup algebras. 相似文献
7.
O. V. Shvartsman 《Functional Analysis and Its Applications》2009,43(2):132-139
Let Γ ? U (1, 1) be the subgroup generated by the complex reflections. Suppose that Γ acts discretely on the domain K = {(z 1, z 2) ∈ ?2 ||z 1|2 ? |z 2|2 < 0} and that the projective group PΓ acts on the unit disk B = {|z 1/z 2| < 1} as a Fuchsian group of signature (n 1, ..., n s ), s ? 3, n i ? 2. For such groups, we prove a Chevalley type theorem, i.e., find a necessary and sufficient condition for the quotient space K/Γ to be isomorphic to ?2 ? {0}. 相似文献
8.
In this paper, we present the conditions on dilation parameter {s
j}j that ensure a discrete irregular wavelet system {s
j
n/2ψ(s
j
·−bk)}
j∈ℤ,k∈ℤ
n
to be a frame on L2(ℝn), and for the wavelet frame we consider the perturbations of translation parameter b and frame function ψ respectively. 相似文献
9.
We determine all tight Lagrangian surfaces in S
2 × S
2. In particular, globally tight Lagrangian surfaces in S
2 × S
2 are nothing but real forms of this symmetric space. 相似文献
10.
Linda Brown Westrick 《Israel Journal of Mathematics》2017,219(1):431-448
A family of sets is union-free if there are no three distinct sets in the family such that the union of two of the sets is equal to the third set. Kleitman proved that every union-free family has size at most (1+o(1))( n/2 n ). Later, Burosch–Demetrovics–Katona–Kleitman–Sapozhenko asked for the number α(n) of such families, and they proved that \({2^{\left( {\begin{array}{*{20}{c}} n \\ {n/2} \end{array}} \right)}} \leqslant \alpha \left( n \right) \leqslant {2^{2\sqrt 2 \left( {\begin{array}{*{20}{c}} n \\ {n/2} \end{array}} \right)\left( {1 + o\left( 1 \right)} \right)}}\) They conjectured that the constant \(2\sqrt 2 \) can be removed in the exponent of the right-hand side. We prove their conjecture by formulating a new container-type theorem for rooted hypergraphs. 相似文献
11.
Dimitra Kosta 《Proceedings of the Steklov Institute of Mathematics》2009,264(1):102-109
Let X be a complete intersection of two hypersurfaces F
n
and F
k
in ℙ5 of degree n and k, respectively, with n ≥ k, such that the singularities of X are nodal and F
k
is smooth. We prove that if the threefold X has at most (n + k − 2)(n − 1) − 1 singular points, then it is factorial. 相似文献
12.
Thomas P. Wakefield 《Algebras and Representation Theory》2011,14(4):609-623
Let G be a finite group and cd(G) be the set of irreducible character degrees of G. Bertram Huppert conjectured that if H is a finite nonabelian simple group such that cd(G) = cd(H), then G ≅ H×A, where A is an abelian group. In this paper, we verify the conjecture for the twisted Ree groups 2
G
2(q
2) for q
2 = 32m + 1, m ≥ 1. The argument involves verifying five steps outlined by Huppert in his arguments establishing his conjecture for many
of the nonabelian simple groups. 相似文献
13.
The partial ordering of Medvedev reducibility restricted to the family of 01 classes is shown to be dense. For two disjoint computably enumerable sets, the class of separating sets is an important example of a 01 class, which we call a ``c.e. separating class'. We show that there are no non-trivial meets for c.e. separating classes, but that the density theorem holds in the sublattice generated by the c.e. separating classes.
Mathematics Subject Classification (2000): 03D30, 03D25 相似文献
14.
15.
Let E be an equivalence relation on the powerset of an uncountable set, which is reasonably definable. We assume that any two subsets with symmetric difference of size exactly 1 are not equivalent. We investigate whether for E there are many pairwise non equivalent sets.
I would like to thank Alice Leonhardt for the beautiful typing.This research was supported by The Israel Science Foundation. Publication 724.
Mathematics Subject Classification (2000): 03E47, 03E35; 20K20, 20K35 相似文献
16.
Siegmund Duality for Continuous Time Markov Chains on ℤ<Stack><Subscript>+</Subscript><Superscript>d</Superscript></Stack> 下载免费PDF全文
Pan Zhao 《数学学报(英文版)》2018,34(9):1460-1472
For the continuous time Markov chain with transition function P(t) on Z+d, we give the necessary and sufficient conditions for the existence of its Siegmund dual with transition function P(t). If Q, the q-matrix of P(t), is uniformly bounded, we show that the Siegmund dual relation can be expressed directly in terms of q-matrices, and a sufficient condition under which the Q-function is the Siegmund dual of some Q-function is also given. 相似文献
17.
Ralph R. Gomez 《Geometriae Dedicata》2011,150(1):249-255
We settle completely an open problem formulated by Boyer and Galicki in [5] which asks whether or not #kS 2 × S 3 are negative Sasakian manifolds for all k. As a consequence of the affirmative answer to this problem, there exists so-called Sasaki η-Einstein and Lorentzian Sasaki-Einstein metrics on these five-manifolds for all k and moreover all of these can be realized as links of isolated hypersurface singularities defined by weighted homogenous polynomials. The key step is to construct infinitely many hypersurfaces in weighted projective space that contain branch divisors \({\Delta=\sum_{i}\left(1-\frac{1}{m_{i}}\right)D_i}\) such that the D i are rational curves. 相似文献
18.
A key tool in recent advances in understanding arithmetic progressions and other patterns in subsets of the integers is certain
norms or seminorms. One example is the norms on ℤ/Nℤ introduced by Gowers in his proof of Szemerédi’s Theorem, used to detect uniformity of subsets of the integers. Another
example is the seminorms on bounded functions in a measure preserving system (associated to the averages in Furstenberg’s
proof of Szemerédi’s Theorem) defined by the authors. For each integer k ≥ 1, we define seminorms on ℓ∞(ℤ) analogous to these norms and seminorms. We study the correlation of these norms with certain algebraically defined sequences,
which arise from evaluating a continuous function on the homogeneous space of a nilpotent Lie group on a orbit (the nilsequences).
Using these seminorms, we define a dual norm that acts as an upper bound for the correlation of a bounded sequence with a
nilsequence. We also prove an inverse theorem for the seminorms, showing how a bounded sequence correlates with a nilsequence.
As applications, we derive several ergodic theoretic results, including a nilsequence version of the Wiener-Wintner ergodic
theorem, a nil version of a corollary to the spectral theorem, and a weighted multiple ergodic convergence theorem. 相似文献
19.
Let
be the Galois ring of characteristic 23 and rank n and let
. We give an explicit construction of Hadamard difference sets in
.}Research supported by NSA grant MDA 904-02-1-0080. 相似文献