Heat Content of a Riemannian Manifold with a Perfect Conducting Boundary

Let M be a compact smooth Riemannian manifold with smooth boundary. We establish the existence of an asymptotic series for the heat content of M with a perfect conducting boundary and show that the coefficients in the series are non-local invariants which are recursively determined by the coefficients for the series with corresponding zero Dirichlet boundary condition.     

理想簇和根理想

关于环的理想的根有两种定义,一种是所有包含I的极大理想的交,另一种是所有包含I的素理想交,本文主要研究后者定义的一些性质,以及和理想簇V(I)(所有包含I的素理想的集合)的关系.     

Semigroup Domination on a Riemannian Manifold with Boundary

We discuss the semigroup domination on a Riemannian manifold with boundary. Our main interest is the Hodge–Kodaira Laplacian for differential forms. We consider two kinds of boundary conditions; the absolutely boundary condition and the relative boundary condition. Our main tool is the square field operator. We also develop a general theory of semigroup commutation.     

On the Manifold of Almost Complex Structures

Let (M, g ₀) be a smooth closed Riemannian manifold of even dimension 2_n admitting an almost complex structure. It is shown that the space of all almost complex structures on M determining the same orientation as the one determined by a fixed almost complex structure J ₀ is a smooth locally trivial fiber bundle over the space of almost complex structures orthogonal with respect to g ₀ and determining the same orientation as J ₀.__________Translated from Matematicheskie Zametki, vol. 78, no. 1, 2005, pp. 66–71.Original Russian Text Copyright © 2005 by N. A. Daurtseva.     

Graphs and Gromov hyperbolicity of non-constant negatively curved surfaces

In this paper we obtain the equivalence of the Gromov hyperbolicity between an extensive class of complete Riemannian surfaces with pinched negative curvature and certain kind of simple graphs, whose edges have length 1, constructed following an easy triangular design of geodesics in the surface.     

模糊幂格的素理想与素对偶理想

讨论格与其模糊幂格的理想,对偶理想的关系,以及格与其模糊幂格的素理想,素对偶的关系.     

Martin Boundary of a Fractal Domain

A uniformly John domain is a domain intermediate between a John domain and a uniform domain. We determine the Martin boundary of a uniformly John domain D as an application of a boundary Harnack principle. We show that a certain self-similar fractal has its complement as a uniformly John domain. In particular, the complement of the 3-dimensional Sierpiski gasket is a uniform domain and its Martin boundary is homeomorphic to the Sierpiski gasket itself.     

Average Growth of the Spectral Function on a Riemannian Manifold

We study average growth of the spectral function of the Laplacian on a Riemannian manifold. Two types of averaging are considered: with respect to the spectral parameter and with respect to a point on a manifold. We obtain as well related estimates of the growth of the pointwise ζ-function along vertical lines in the complex plane. Some examples and open problems regarding almost periodic properties of the spectral function are also discussed.     

Apollonian度量与Apollonian边界条件

证明了(1)■中真子域D上的Apollonian度量αD是拟共形映射的拟不变量;(2)■中严格一致域是拟共形不变的;(3)■中的Jordan域D是拟圆当且仅当D是严格一致域,作为应用,进一步得到了Apollonian边界条件,拟共形映射和局部Lipschitz映射之间的关系。     

The Kernel of the Eisenstein Ideal

Let N be a prime number, and let J₀(N) be the Jacobian of the modular curve X₀(N). Let T denote the endomorphism ring of J₀(N). In a seminal 1977 article, B. Mazur introduced and studied an important ideal I⊆T, the Eisenstein ideal. In this paper we give an explicit construction of the kernel J₀(N)[I] of this ideal (the set of points in J₀(N) that are annihilated by all elements of I). We use this construction to determine the action of the group Gal(Q/Q) on J₀(N)[I]. Our results were previously known in the special case where N−1 is not divisible by 16.     

The decision of prime and primary ideal

We give more efficient criteria to characterise prime ideal or primary ideal. Further, we obtain the necessary and sufficient conditions that an ideal is prime or primary in real field from the Gröbner bases directly.     

半环上同余的刻画

引入半环的完全素理想的概念.利用这一概念,研究了半环的同余,分别给出了半环的子直积分解的若干结果和半环同余的一种刻画.     

Boundary stabilization of wave equations with variable coefficients

The aim of this paper is to obtain the exponential energy decay of the solution of the wave equation with variable coefficients under suitable linear boundary feedback. Multiplier method and Riemannian geometry method are used.     

凸域上拟双曲测地线直径的Gehring-Hayman 恒等式

利用型函数和最大项m（σ）的几何意义研究全平面上Dirichlet级数的增长性,得到了Dirichlet级数增长性与系数、指数之间关系的四个结论,推广了以往研究增长性的相关结果.     

The Minimal Length of a Closed Geodesic Net on a Riemannian Manifold with a Nontrivial Second Homology Group

Let Mⁿ be a closed Riemannian manifold with a nontrivial second homology group. In this paper we prove that there exists a geodesic net on Mⁿ of length at most 3 diameter(Mⁿ). Moreover, this geodesic net is either a closed geodesic, consists of two geodesic loops emanating from the same point, or consists of three geodesic segments between the same endpoints. Geodesic nets can be viewed as the critical points of the length functional on the space of graphs immersed into a Riemannian manifold. One can also consider other natural functionals on the same space, in particular, the maximal length of an edge. We prove that either there exists a closed geodesic of length ≤ 2 diameter(Mⁿ), or there exists a critical point of this functional on the space of immersed θ-graphs such that the value of the functional does not exceed the diameter of Mⁿ. If n=2, then this critical θ-graph is not only immersed but embedded.Mathematics Subject Classifications (2000). 53C23, 49Q10     

Quantale中的素理想及弱素理想

本文把Quantale中的序结构与代数运算＆结合在一起给出了Quantale中素理想和弱素理想的概念。讨论了它们之间的关系,得到了Quantale中理想是(弱)素理想的充要条件。证明了与序半群中的一些经典结论相一致的命题。     

On the curvature of the diffeomorphisms group

An expression for the sectional curvature ofSDIFF(M) (the group of diffeomorphism preserving Riemannian density on a closed manifoldM) is obtained. In the case of a locally Euclidean manifoldM, the negativeness of curvature that implies the instability of solutions of Euler equations of ideal incompressible fluids onM is established.     

The Stable Class of the Augmentation Ideal

In [F.E.A. Johnson, Stable Modules and the D(2)-Problem, LMS Lecture Notes In Mathematics, vol. 301, CUP (2003)], for finite groups G, we gave a parametrization of the stable class of the augmentation ideal of Z[G] in terms of stably free modules. Whilst the details of this parametrization break down immediately for infinite groups, nevertheless one may hope to find parallel arguments for restricted classes of infinite groups. Subject to the restriction that Ext¹(Z, Z[G]) = 0, we parametrize the minimal level in Ω₁(Z) by means of stably free modules and give a lower estimate for the size of Ω₁(Z).     

The Logarithmic Gradient of the Kernel of the Heat Equation with Drift on a Riemannian Manifold

For a parabolic equation with drift on a Riemannian manifold of positive curvature we obtain a representation for the logarithmic gradient in the form of the sum of two vector fields one of which is known and the other is bounded. The drift field is assumed to be of sufficiently rapid decay at infinity.