TENSOR PRODUCTS OF JACOBSON RADICALS IN NEST ALGEBRAS

This paper studies the tensor product RN RM of Jacobson radicals in nest algebras, and obtains that RN RM = {T∈B(H1 H2) : T(N M)(?)N_ M_, N∈N,M∈M}; and based on the characterization of rank-one operators in RN RM,it is proved that if N, M are non-trivial then RN RM=R if and only if N, M are continuous.     

A global solution of the Einstein-Yang-Mills equation on the conformal space

The method used to construct the SU(2) Yang-Mills field on a compactified Minkowski space-M(which is equivalent to the conformal space) is generalized to construct an SU(N)(N > 2) Yang-Mills fieldFjκ on M. It is proved that both Fjκ and the invariant metric tensor gjκ of M satisfy the Einstein-Yang-Mills equation. The case of N →∞ is also discussed.     

ON EULER CHARACTERISTIC OF MODULES~(**)

This paper gives a characteristic property of the Euler characteristic for IBN rings. The following results: are proved. (1) If R is a commutative ring, M, N are two stable free R-modules, then χ(MN)=χ(M)χ(N), where χ denotes the Euler characteristic. (2) If f: K_0(R)→Z is a ring isomorphism, where K_0(R) denotes the Grothendieck group of R, K_0(R) is a ring when R is commutative, then f([M])=χ(M) and χ(MN)=χ(M)χ(N) when M, N are finitely generated projective R-modules, where.the isomorphism class [M] is a generator of K_0(R). In addition, some applications of the results above are also obtained.     

关于M／M~［r］／1系统的一个注记

徐光辉［１，第六章§１］讨论了成批服务系统Ｍ／Ｍ［ｒ］／１，并在ｌｉｍＰｊ（ｔ）＝Ｐｊ＞０假设下，求出马氏过程Ｎ（ｔ）的平稳分布｛Ｐｉ｝，李文琦等在［２，Ｐ１６８８］指出［１．Ｐ２１８—２１９］给出的关于ｌｉｍＰｊ（ｔ）＝Ｐｊ＞０的证明是不准确的，并利用Ｆｏｓｔｅｒ判别法给出Ｎ（ｔ）的遍历性的严格证明。本文指出Ｎ（ｔ）的遍历性可由Ｐｉｊ（△ｔ）的表达式及Ｔａｋａｃｓ［４，Ｐ９４定理２］推出。     

REGULARITY OF HARMONIC MAPS INTO POSITIVELY CURVED MANIFOLDS

Let M be a compact Riemannian manifold of dimension m, N a complete Amply connected δ-pinched Riemannian manifold of dimension n. There exists a constant d(n). It is proved that if m≤d(n), then every minimizing map from M into N is smooth in the interior of M. If m=d(n)+1, such a map has at most diserete singular set and in general the Hausdorff dimension of the singular set is at most m-d(n)-1.     

Hamiltonian structure of M. Sato's hierarchy of Kadomtsev-Petviashvili equation

Summary The Hamiltonian structure of M. Sato's hierarchy of higher order Kadomtsev-Petviashvili (KP) equation is derived. It is proved that KP equation is Hamiltonian equation of motion on the coadjoint orbit of a certain formal Lie group. Furthermore it possesses a family of infinitely many conserved densities which is in involution.     

流形上的Riesz变换

设 Ｍ为一完备 Ｒｉｅｍａｎｎ流形, Ｓｔｒｉｃｈａｒｔｚ Ｒ． Ｓ, Ｌｏｈｏｕｅ Ｎ．, Ｂａｋｒｙ Ｄ．及作者等建立了 Ｍ上 Ｒｉｅｓｚ变换Ｒ的 Ｌ~ｐ（１＜ Ｐ＜ ∞）与弱型（１,１）有界性．本文将用分析的方法对曲率非负的流形建立Ｒ的Ｌ*－有界性．     

Spectral theory, Hausdorff dimension and the topology of hyperbolic 3-manifolds

Let M be a compact 3-manifold whose interior admits a complete hyperbolic structure. We let Λ(M) be the supremum of λ₀(N) where N varies over all hyperbolic 3-manifolds homeomorphic to the interior of N. Similarly, we let D(M) be the infimum of the Hausdorff dimensions of limit sets of Kleinian groups whose quotients are homeomorphic to the interior of M. We observe that A(M) = D(M)(2 − D(M)) if M is not handlebody or a thickened torus. We characterize exactly when A(M) = 1 and D(M) = 1 in terms of the characteristic submanifold of the incompressible core of M.     

关于环的交换性定理

令R为有单位元的结合环,M(R)=N(R)∪J/(R).证明了如果存在正整数m使得所有x,y∈_R\M(R)均满足(xy)~k=x^ky^k(其中k=m,m+1,m+2);或者使得所有x,y∈R\M(R)均满足(xy)~k=y^kx^k(其中k=m-1,m,m+1为正整数),那么R是交换环.     

Minimal cyclic random motion in and hyper-Bessel functions

We obtain the explicit distribution of the position of a particle performing a cyclic, minimal, random motion with constant velocity c in . The n+1 possible directions of motion as well as the support of the distribution form a regular hyperpolyhedron (the first one having constant sides and the other expanding with time t), the geometrical features of which are here investigated.The distribution is obtained by using order statistics and is expressed in terms of hyper-Bessel functions of order n+1. These distributions are proved to be connected with (n+1)th order p.d.e. which can be reduced to Bessel equations of higher order.Some properties of the distributions obtained are examined. This research has been inspired by a conjecture formulated in Orsingher and Sommella [E. Orsingher, A.M. Sommella, A cyclic random motion in R³ with four directions and finite velocity, Stochastics Stochastics Rep. 76 (2) (2004) 113–133] which is here proved to be false.     

Evolution equations with a free boundary condition

In this paper we consider the heat flow of harmonic maps between two compact Riemannian Manifolds M and N (without boundary) with a free boundary condition. That is, the following initial boundary value problem ∂₁,u −Δu = Γ(u)(∇u, ∇u) [tT T_{u u}N, on M × [0, ∞), u(t, x) ∈ Σ, for x ∈ ∂M, t > 0, ∂u/t6n(t, x) ⊥_u T_u(t,x) Σ, for x ∈ ∂M, t > 0, u(o,x) = u_o(x), on M, where Σ is a smooth submanifold without boundary in N and n is a unit normal vector field of M along ∂M. Due to the higher nonlinearity of the boundary condition, the estimate near the boundary poses considerable difficulties, even for the case N = ℝⁿ, in which the nonlinear equation reduces to ∂_tu-Δu = 0. We proved the local existence and the uniqueness of the regular solution by a localized reflection method and the Leray-Schauder fixed point theorem. We then established the energy monotonicity formula and small energy regularity theorem for the regular solutions. These facts are used in this paper to construct various examples to show that the regular solutions may develop singularities in a finite time. A general blow-up theorem is also proven. Moreover, various a priori estimates are discussed to obtain a lower bound of the blow-up time. We also proved a global existence theorem of regular solutions under some geometrical conditions on N and Σ which are weaker than K_N <-0 and Σ is totally geodesic in N.     

Application of Malliavin calculus to a class of stochastic differential equations

Summary In this article we deal with stochastic differential equations driven by an infinite dimensional Brownian motion. Under some non-degeneracy conditions, the existence and smoothness of the density for the law of the solution is proved.The work of Nguyen Minh Duc was done during a stay at the University of Barcelona (Spain)The work of D. Nualart and M. Sanz has been supported by the Grant of the C.Y.C.I.T. number PB86-0238     

Elliptic curves and their torsion subgroups over number fields of type (2, 2,

Suppose that E：y2=x(x+M)(x+N) is an elliptic curve, where M相似文献   

Direct Limits and Inverse Limits of SHR Semigroups

In this paper, it is proved that the direct limit (inverse limit) of an SHR direct (respectively, inverse) family of SHR semigroups is an SHR semigroup.AMS Subject Classifications Primary 20N20 Secondary 20M99     

具无限时滞线性中立型泛函微分方程周期解

本文证明了具无限时滞D算子型线性中立型泛函微分方程存在周期解当且仅当存在有界解,推广了MasseraJ．L,ChowS．N．和MakayM．的结果．     

Banach operator pairs,common fixed-points,invariant approximations,and ∗ -nonexpansive multimaps

Common fixed-point results are proved for I$I$-nonexpansive maps, Ciric type maps, and ∗-nonexpansive multimaps. Invariant approximation results are obtained for these types of maps as applications. Our results extend or generalize several known results including the recent results of Chen and Li [J. Chen, Z. Li, Common fixed-points for Banach operators pairs in best approximation, J. Math. Anal. Appl. 336 (2007) 1466–1475]. In particular, we show that the results of Chen and Li on Banach operator pairs are particular cases of the results of Al-Thagafi and Shahzad [M.A. Al-Thagafi, N. Shahzad, Noncommuting selfmaps and invariant approximations, Nonlinear Anal. 64 (2006) 2778–2786].     

Analytic intermediate dimensional elliptic tori for the planetary many-body problem

In our context,the planetary many-body problem consists of studying the motion of(n+1)-bodies under the mutual attraction of gravitation,where n planets move around a massive central body,the Sun.We establish the existence of real analytic lower dimensional elliptic invariant tori with intermediate dimension N lies between n and 3n-1 for the spatial planetary many-body problem.Based on a degenerate KolmogorovArnold-Moser(abbr.KAM)theorem proved by Bambusi et al.(2011),Berti and Biasco(2011),we manage to handle the difficulties caused by the degeneracy of this real analytic system.     

Non-divergence form operators and variations on Yau's explosion criterion

Let † denote the standard (i.e., Levi-Civita) Laplacian for some non-compact, connected, complete, separable Riemannian manifild M. In a much cited article, Yau [5] proved that when the Ricci curvature is bounded uniformly below, then the only bounded solution to the heat equation ∂ _t μ=Δμ on [0, ∞) × M which vanishes at t=0 is the one which vanishes evarywhere. Equivalently, no matter where it starts, Brownian motion on M never explodes. Yau's original statement was improved or extended in various directions by a long list of authors. With this paper, the present author joins the list.     

ON THE TOPOLOGY,VOLUME,DIAMETER AND GAUSS MAP IMAGE OF SUBMANIFOLDS IN A SPHERE

In this paper, the author uses Gauss map to study the topology, volume and diameter of submanifolds in a sphere. It is proved that if there exist ε, 1≥ε > 0 and a fixed unit simple p-vector a such that the Gauss map g of an n-dimensional complete and connected submanifold M in Sn p satisfies (g, a) ≥ε, then M is diffeomorphic to Sn, and the volume and diameter of M satisfy εnvol(Sn) ≤vol(M) ≤ vol(Sn)/ε and επ ≤diam(M) ≤ π/ε, respectively. The author also characterizes the case where these inequalities become equalities. As an application, a differential sphere theorem for compact submanifolds in a sphere is obtained.     

Pseudofinite homogeneity, isolation, and reducibility

It has been proved (by S. M. Dudakov and M. A. Taitslin) that the reducibility of some models of a theory implies the second pseudofinite homogeneity property for this theory. We prove the converse, namely, that any theory with the first or the second pseudofinite homogeneity property has a reducible model and, therefore, possesses the second isolation property. This also proves the equivalence of the second isolation property and the second pseudofinite homogeneity property, in contrast to the first pseudofinite homogeneity property, which is more general than the first isolation property (this was established by O. V. Belegradek, A. P. Stolboushin, and M. A. Taitslin).