Amenability,Poincaré级数算子与Teichmüller距离

设Y→X为双曲型Riemann曲面X的覆盖映射,它诱导了X与Y的Teichmller空间之间的一个映射T(X)→T(Y),得到了i)覆盖Y→X为amenable的充分必要条件是诱导映射T(X)→T(Y)对于Teichmller度量为整体等距;ii)诱导映射T(X)→T(Y)为收缩的充分必要条件是对于任意的[μ]∈T(X),都有||_[μ]||<1,其中_[μ]为Poincar级数算子;iii)诱导映射T(X)→T(Y)在T(X)上不是一致收缩的.     

Asymptotic Representation of L<Subscript>p</Subscript>-Minimal Polynomials, 1 < p < ∞

While the theory of asymptotics for L₂-minimal polynomials is highly developed, so far not much is known about L_p-minimal polynomials, Indeed, Bernstein gave asymptotics for the minimum deviation, Fekete and Walsh gave nth root asymptotics and, recently, Lubinsky and Saff came up with asymptotics outside the support [-1,1]. But the main point of interest, the asymptotic representation on the support, still remains open. Here we settle it for weight functions of the form where w is positive and on [-1,1] with and 相似文献   

On automorphisms of distance-regular graphs with intersection arrays {2<Emphasis Type="Italic">r</Emphasis> + 1, 2<Emphasis Type="Italic">r</Emphasis> − 2, 1; 1, 2, 2<Emphasis Type="Italic">r</Emphasis> + 1}

Let Γ be an antipodal graph with intersection array {2r+1, 2r?2, 1; 1, 2, 2r+1}, where 2r(r + 1) ≤ 4096. If 2r + 1 is a prime power, then Mathon’s scheme provides the existence of an arc-transitive graph with this intersection array. Note that 2r + 1 is not a prime power only for r ∈ {7, 17, 19, 22, 25, 27, 31, 32, 37, 38, 42, 43}. We study automorphisms of hypothetical distance-regular graphs with the specified values of r. The cases r ∈ {7, 17, 19} were considered earlier. We prove that, if Γ is a vertex-symmetric graph with intersection array {2r + 1, 2r ? 2, 1; 1, 2, 2r +1}, 2r + 1 is not a prime power, and r ≤ 43, then r = 25, 27, or 31.     

(l,l,…,l)型数域

设K~n是Abel数域,Gal(Kⁿ/Q)≌(Z/lZ)ⁿ。本文对一般素数l,一般n刻画了Kⁿ的结构。特别是完全解决了Kⁿ的判别式密度问题,即明显给出ⅰ)Kⁿ的判别式。ⅱ)判别式为D的Kⁿ的个数J(D)。ⅲ)判别式小于X的Kⁿ的个数N(X)～,C是明显给出常数(l=2情形引作者另文)。Hasse,Cohn,Baily等的结果作为特殊情形含于本文结果之中。     

Strongly almost (<Emphasis Type="Italic">ω, λ, q</Emphasis>)-summable sequences

The purpose of this paper is to introduce the spaces of sequences that are strongly almost (ω, λ, q)-summable with respect to a modulus function. We give some relations related to these sequence spaces. It is also shown that if a sequence is strongly (ω, λ, q)-summable with respect to a modulus function, then it is S(λ _q )-statistically convergent.     

The Bellman function,the two-weight Hilbert transform,and embeddings of the model spaces<Emphasis Type="Italic">K</Emphasis><Subscript>θ</Subscript>

This paper is devoted to embedding theorems for the spaceK _θ , where θ is an inner function in the unit disc D. It turns out that the question of embedding ofK _θ into L²(Μ) is virtually equivalent to the boundedness of the two-weight Hilbert transform. This makes the embedding question quite difficult (general boundedness criteria of Hunt-Muckenhoupt-Wheeden type for the twoweight Hilbert transform have yet to be found). Here we are not interested in sufficient conditions for the embedding ofKg into L²(Μ) (equivalent to a certain two-weight problem for the Hilbert transform). Rather, we are interested in the fact that a certain natural set of conditions is not sufficient for the embedding ofK _θ intoL ² (Μ) (equivalently, a certain set of conditions is not sufficient for the boundedness in a two-weight problem for the Hilbert transform). In particular, we answer (negatively) certain questions of W. Cohn about the embedding ofK _θ into L²(Μ). Our technique leads naturally to the conclusion that there can be a uniform embedding of all the reproducing kernels ofK _θ but the embedding of the wholeK _θ intoL ²(Μ) may fail. Moreover, it may happen that the embedding into a potentially larger spaceL ²(μ) fails too. Both authors are supported by the NSF grant DMS 9970395 and joint American-Israeli grant BSF 00030.     

QUANDLE VARIETIES,GENERALIZED SYMMETRIC SPACES,AND <Emphasis Type="Italic">φ</Emphasis>-SPACES

We define a quandle variety as an irreducible algebraic variety Q endowed with an algebraically defined quandle operation ?. It can also be seen as an analogue of a generalized affine symmetric space or a regular s-manifold in algebraic geometry.Assume that Q is normal as an algebraic variety and that the action of its inner automorphism group Inn(Q) has a dense orbit. Then we show that there is an algebraic group G acting on Q with the same orbits as Inn(Q) such that each G-orbit is isomorphic to the quandle (G/H, ?φ) associated to the group G, an automorphism φ of G and a subgroup H of Gφ.     

Metric,Banach, and Hilbert Spaces of <Emphasis Type="Italic">φB</Emphasis>-Distributions

We introduce φ-distributions and prove that their set is ametric space. We also consider a Banach space and a Hilbert space of such distributions. The results are applied to differential equations with Laurent’s type coefficients.     

Extended Srivastava’s triple hypergeometric <Emphasis Type="Italic">H</Emphasis><Subscript><Emphasis Type="Italic">A,p,q</Emphasis></Subscript> function and related bounding inequalities

In this paper, motivated by certain recent extensions of the Euler’s beta, Gauss’ hypergeometric and confluent hypergeometric functions (see [4]), we extend the Srivastava’s triple hypergeometric function H _A by making use of two additional parameters in the integrand. Systematic investigation of its properties including, among others, various integral representations of Euler and Laplace type, Mellin transforms, Laguerre polynomial representation, transformation formulas and a recurrence relation, is presented. Also, by virtue of Luke’s bounds for hypergeometric functions and various bounds upon the Bessel functions appearing in the kernels of the newly established integral representations, we deduce a set of bounding inequalities for the extended Srivastava’s triple hypergeometric function H _A,p,q .     

Marcus–Lushnikov processes,Smoluchowski’s and Flory’s models

The Marcus–Lushnikov process is a finite stochastic particle system in which each particle is entirely characterized by its mass. Each pair of particles with masses x$x$ and y$y$ merges into a single particle at a given rate K(x,y)$K(x,y)$. We consider a strongly gelling   kernel behaving as K(x,y)=x^αy+xy^α$K(x,y)=x^{\alpha }y+x{y}^{\alpha }$ for some α∈(0,1]$\alpha \in (0,1]$. In such a case, it is well-known that gelation occurs, that is, giant particles emerge. Then two possible models for hydrodynamic limits of the Marcus–Lushnikov process arise: the Smoluchowski equation, in which the giant particles are inert, and the Flory equation, in which the giant particles interact with finite ones.     

Convex polynomial and spline approximation inL p,O<p<∞

We prove that a convex functionf ∈ L _p[−1, 1], 0<p<∞, can be approximated by convex polynomials with an error not exceeding Cω ₃ ^ϕ (f,1/n)_p where ω ₃ ^ϕ (f,·) is the Ditzian-Totik modulus of smoothness of order three off. We are thus filling the gap between previously known estimates involving ω ₃ ^ϕ (f,1/n)_p, and the impossibility of having such estimates involving ω₄. We also give similar estimates for the approximation off by convexC ⁰ andC ¹ piecewise quadratics as well as convexC ² piecewise cubic polynomials. Communicated by Dietrich Braess     

On Tanaka formulae for (α, <Emphasis Type="Italic">d</Emphasis>, β)-superprocesses

In this paper, Tanaka formulae for (α, d, β)-superprocesses in the dimensions where the local time exists are established under the optimal initial condition.     

Cuts,Trees and ℓ<Subscript>1</Subscript>-Embeddings of Graphs*

Motivated by many recent algorithmic applications, this paper aims to promote a systematic study of the relationship between the topology of a graph and the metric distortion incurred when the graph is embedded into ₁ space. The main results are:1. Explicit constant-distortion embeddings of all series-parallel graphs, and all graphs with bounded Euler number. These are the first natural families known to have constant distortion (strictly greater than 1). Using the above embeddings, algorithms are obtained which approximate the sparsest cut in such graphs to within a constant factor.2. A constant-distortion embedding of outerplanar graphs into the restricted class of ₁-metrics known as dominating tree metrics. A lower bound of (log n) on the distortion for embeddings of series-parallel graphs into (distributions over) dominating tree metrics is also presented. This shows, surprisingly, that such metrics approximate distances very poorly even for families of graphs with low treewidth, and excludes the possibility of using them to explore the finer structure of ₁-embeddability.* A preliminary version of this work appeared in Proceedings of the 40th Annual IEEE Symposium on Foundations of Computer Science, 1999, pp. 399–408. This work was done while the author was at the University of California, Berkeley. Supported in part by NSF grants CCR-9505448 and CCR-9820951.     

(2,2,…,2)型代数函数域

本文基于文献[1—4]的有关结果系统地研究了2ⁿ次扩域 L=k(√D₁(t)…,√(D_n(t),D_i(t)∈F_q[t], 特别决定了L/k的分类,素分解规律,整基,判别式,亏格;定义并确定了L/k的导子;确定了L/k的ζ-函数;最后证明了L的理想类数为,L的(零次)除子类数为,其中K_v过L/k的二次子扩张,Q为单位指数,m∈Z明显给出。后两公式的证明涉及较复杂的计算。这些结果是上述关于k的二次扩张结果的推广。基于这些结果及MacRae,Madan的若干结果,我们在相继的论文中确定了h(L)=1的全部域L,以及h(O_L)=1,n=2的全部虚域L。     

Largest <Emphasis Type="Italic">E</Emphasis>-thin, <Emphasis Type="Italic">E</Emphasis>-invariant sets below Δ<Superscript>1</Superscript><Subscript>3</Subscript>

In this paper, we construct, by effective induction, a ¹₁ equivalence relation E on for which there is no largest E-thin E-invariant ¹₁ subset of by effective induction. This result answers a problem asked by Kechris in [1]Mathematics Subject Classification: 03E15Revised version: 13 January 2000     

Characterizations of PG(n − 1, q)\PG(k − 1, q) by Numerical and Polynomial Invariants

We show that the simple matroid PG(n − 1, q)\PG(k − 1, q), for n ≥ 4 and 1 ≤ k ≤ n − 2, is characterized by a variety of numerical and polynomial invariants. In particular, any matroid that has the same Tutte polynomial as PG(n − 1, q)\PG(k − 1, q) is isomorphic to PG(n − 1, q)\PG(k − 1, q).     

Containment of c<Subscript>0</Subscript> and ℓ<Subscript>1</Subscript> in π<Subscript>1</Subscript>(<Emphasis Type="Italic">E,F</Emphasis>)

Suppose π₁(E, F) is the space of all absolutely 1-summing operators between two Banach spacesE andF. We show that ifF has a copy of c₀, then π₁ (E, F) will have a copy of c₀, and under some conditions ifE has a copy of ℓ₁ then π₁ (E, F) would have a complemented copy of ℓ₁.