数学学报英文版Vol.21(2005),No.5论文摘要(英文)

<正>Let D=P1 P2…Pm, where P1, P2,…, Pm are distinct rational primes with P1≡P2≡3(mod 8), Pi≡1(mod 8)(3≤i≤m), and m is any positive integer. In this paper, we give a simple combinatorial criterion for the value of the complex L-function of the congruent elliptic curve E_(D~2): y~2=x~3-D~2 x at s=1, divided by the period w defined below, to be exactly divisible by 2~(2m-2), the second lowest 2-power with respect to the number of the Gaussian prime factors of D. As a corollary, we obtain a new series of non-congruent numbers whose prime factors can be arbitrarily many. Our result is in accord with the predictions of the conjecture of Birch and Swinnerton-Dyer.     

SU(m+n)SU(m)×SU(n) ISOSCALAR FACTORS AND S(f_1+f_2)S(f_1)×S(f_2) OUTER-PRODUCT ISOSCALAR FACTORS

It is proved that the SU(m+n)SU(m)×SU(n) isoscalar factors (ISF) are equal to the S(f_1+f_2) outer-product ISF of the permutation group. Since the latter only depend on the partition labels, the values of the SU(m+n)SU(m)×SU(n) ISF do not depend on m and n explicitely. Consequently for a f(=f_1+f_2)-particle system, by evaluating the S(f) S(f_1)×S(f_2) outer-product ISF we can obtain all (an infinite number) of the SU (m+n) SU(m)×SU(n) ISF (or the f_2-particle coefficients of fractional parentage) for arbitrary m and n at a single stroke, in stead of one m and one n at a time. A simple method, the eigenfunction method, is given for evaluating the SU(m+n) SU(m)×SU(n) single particle ISF, while the many-particle ISF can be calculated in terms of the outer-product reduction coefficients and the transformation coefficients from the Yamanouchi basis to the S(f_1+f_2) S(f_1)×S(f_2) basis.     

SOME LIMIT PROPERTIES AND THE GENERALIZED AEP THEOREM FOR NONHOMOGENEOUS MARKOV CHAINS

Let(ξ_n)_(n=0)~∞ be a Markov chain with the state space X = {1, 2, ···, b},(g_n(x, y))_(n=1)~∞ be functions defined on X × X, and F_(m_n,b_n)(ω) =1 /b_n sum from k=m_n+1 to m_n+b_n g_k(ξ_(k-1), ξ_k).In this paper the limit properties of F_(m_n,b_n)(ω) and the generalized relative entropy density f_(m_n,b_n)(ω) =-(1/b_n) log p(ξ_(m_n,m_n+b_n)) are discussed, and some theorems on a.s. convergence for(ξ_n)_n=0~∞ and the generalized Shannon-McMillan(AEP) theorem on finite nonhomogeneous Markov chains are obtained.     

Angular distribution in complex oscillation theory

Let f_1 and f_2 be two linearly independent solutions of the differential equationf″ Af=0,where A is an entire function.Set E=f_1f_2.In this paper,we shall studythe angular distribution of E and establish a relation between zero accumulation rays andBorel directions of E.Consequently we can obtain some results in the complex differentialequation by using known results in angular distribution theory of meromorphic functions.     

On the Functional Estimation and Its Applications

In this paper, the following results are obtained. The functional estimation theorem: Let X, Y be linear spaces, normedbu ‖·‖_X, ‖·‖_Y, respectively: X be a subspace of X: Y(?)Y. Suppose that F is a functional on X×Y to [0, ∞). which has the properties : F(f_1 f_2, g) F(f_1, g) F(f_2, g), and F(f, g)相似文献   

Context-free grammars for triangular arrays

We consider context-free grammars of the form G = {f → fb1+b2+1ga1+a2, g → fb1 ga1+1},where ai and bi are integers sub ject to certain positivity conditions. Such a grammar G gives rise to triangular arrays {T(n, k)}0≤k≤n satisfying a three-term recurrence relation. Many combinatorial sequences can be generated in this way. Let Tn (x) =∑nk=0T(n, k)xk. Based on the differential operator with respect to G, we define a sequence of linear operators Pn such that Tn+1(x) = Pn(Tn(x)). Applying the characterization of real stability preserving linear operators on the multivariate polynomials due to Borcea and Br?ndén, we obtain a necessary and sufficient condition for the operator Pn to be real stability preserving for any n. As a consequence, we are led to a sufficient condition for the real-rootedness of the polynomials defined by certain triangular arrays, obtained by Wang and Yeh.Moreover, as special cases we obtain grammars that lead to identities involving the Whitney numbers and the Bessel numbers.     

高阶Schr(o..)dinger方程的一族恒稳差分格式

A family of three-layer implicit difference schemes of high accuracy with two parameters for solving high order Schroedinger type equation au/at = i(-1)^m a^2mu/ax^2m are constructed(where i = √-1,m is positive integers). In the special case α =1/2,β = 0,we obtain a two-layer difference scheme. These schemes are proved to be absolutely stable for arbitrarily chosen non-negative parameters, and the order of the truncation error is O((△t)^2 (△x)^4). They are shown by numerical examples to be effective, and practice consistant with theoretical analysis.     

本刊英文版Vol.27(2011),No.3论文摘要(英文)

<正>Group Connectivity and Group Colorings of Graphs—A Survey Hong-Jian LAI Xiangwen LI Yehong SHAO Mingquan ZHAN Abstract In 1950s,Tutte introduced the theory of nowhere-zero flows as a tool to investigate the coloring problem of maps,together with his most fascinating conjectures on nowhere-zero flows.These have been extended by Jaeger et al.in 1992 to group connectivity,the nonhomogeneous form of nowhere-zero flows.Let G be a 2-edge-connected undirected graph,A be an (additive) abelian group and A* = A - {0}.The graph G is A-connected if G has an orientation D(G) such that for every map b:V(G)(?) A satisfying∑_(v∈V(G)) b(v) = 0,there is a function f:E(G)(?) A* such that for each vertex v∈V(G),the total amount of f-values on the edges directed out from v minus the total amount of f-values on the edges directed into v is equal to     

ON DOUBLY WARPED PRODUCT OF COMPLEX FINSLER MANIFOLDS

Let(M_1,F_1) and(M_2,F_2) be two strongly pseudoconvex complex Finsler manifolds.The doubly wraped product complex Finsler manifold(f_2M_1×f_1 M_2,F) of(M_1,F_1)and(M_2,F_2) is the product manifold M_1×M_2 endowed with the warped product complex Finsler metric F~2 =f_2~2 F_1~2 + f_1~2F_2~2,where f_1 and f_2 are positive smooth functions on M_1 and M2,respectively.In this paper,the most often used complex Finsler connections,holomorphic curvature,Ricci scalar curvature,and real geodesics of the DWP-complex Finsler manifold are derived in terms of the corresponding objects of its components.Necessary and sufficient conditions for the DWP-complex Finsler manifold to be Kahler Finsler(resp.,weakly Kahler Finsler,complex Berwald,weakly complex Berwald,complex Landsberg) manifold are obtained,respectively.It is proved that if(M_1,F_1) and(M_2,F_2) are projectively flat,then the DWP-complex Finsler manifold is projectively flat if and only if f_1 and f_2 are positive constants.     

On the primitive divisors of the recurrent sequence u_(n+1)=(4cos~2(2π/7)-1)u_n-u_(n-1) with applications to group theory

Consider the sequence of algebraic integers un given by the starting values u0=0,u1=1 and the recurrence u_(n+1)=(4cos~2(2π/7)-1)u_n-u_(n-1).We prove that for any n ■{1,2,3,5,8,12,18,28,30}the n-th term of the sequence has a primitive divisor in Z[2 cos(2π/7)].As a consequence we deduce that for any sufficiently large n there exists a prime power q such that the groupcan be generated by a pair x,y with χ~2=y~3=(xy)~7=1 and the order of the commutator[x,y]is exactly n.The latter result answers in affirmative a question of Holt and Plesken.     

Basic functions and unramified local L-factors for split groups

According to a program of Braverman, Kazhdan and Ng, for a large class of split unramified reductive groups G and representations ρ of the dual group G, the unramified local L-factor L(s, π, ρ) can be expressed as the trace of π(f_(ρ,s)) for a function f_(ρ,s) with non-compact support whenever Re(s)0. Such a function should have useful interpretations in terms of geometry or combinatorics, and it can be plugged into the trace formula to study certain sums of automorphic L-functions. It also fits into the conjectural framework of Schwartz spaces for reductive monoids due to Sakellaridis, who coined the term basic functions; this is supposed to lead to a generalized Tamagawa-Godement-Jacquet theory for(G, ρ). In this paper, we derive some basic properties for the basic functions f_(ρ,s) and interpret them via invariant theory. In particular, their coefficients are interpreted as certain generalized Kostka-Foulkes polynomials defined by Panyushev. These coefficients can be encoded into a rational generating function.     

本刊英文版Vol.27(2011),No.4论文摘要(英文)

<正>Distribution of a Certain Partition Function Modulo Powers of Primes Hei-Chi CHAN Abstract In this paper,we study a certain partition function a(n) defined by∑_n≥0 a(n)q~n :=П_(n=1)(1 - q~n)~(-1)(1 - q~(2n)~(-1).We prove that given a positive integer j≥1 and a prime m≥5, there are infinitely many congruences of the type a(An + B)≡0(mod m~j).This work is inspired by Ono's ground breaking result in the study of the distribution of the partition function p(n).     

Hardy Spaces H_L~p(R~n) Associated with Higher-Order Schrdinger Type Operators

Let L = L0+V be the higher order Schrdiger type operator where L0 is a homogeneous elliptic operator of order 2m in divergence form with bounded coefficients and V is a real measurable function as multiplication operator(e.g., including(-?)m+V(m∈N) as special examples). In this paper, assume that V satisfies a strongly subcritical form condition associated with L0, the authors attempt to establish a theory of Hardy space Hp L(Rn)(0 p ≤ 1) associated with the higher order Schrdinger type operator L. Specifically, we first define the molecular Hardy space Hp L(Rn) by the so-called( p, q, ε, M) molecule associated to L and then establish its characterizations by the area integral defined by the heat semigroup e-t L.     

The Poincaré Series of Relative Invariants of Finite Pseudo-Reflection Groups

Let F be a field with characteristic 0,V=F~n the n-dimensional vector space over F and let G be a finite pseudo-reflection group which acts on V.Let χ:G→F~* be a 1-dimensional representation of G.In this article we show that X(g)=(detg)~α(0≤α≤r-1),where g∈G and r is the order of g.In addition,we characterize the relation between the relative invariants and the invariants of the group G,and then we use Molien's Theorem of invariants to compute the Poincaré series of relative invariants.     

Boundedness of High Order Commutators of Riesz Transforms Associated with Schrödinger Type Operators

Let L_2=(-?)~2+ V~2 be the Schr?dinger type operator, where V■0 is a nonnegative potential and belongs to the reverse H?lder class RH_(q1) for q_1 n/2, n ≥5. The higher Riesz transform associated with L_2 is denoted by ■and its dual is denoted by ■. In this paper, we consider the m-order commutators [b~m, R] and [b~m, R*], and establish the(L~p, L~q)-boundedness of these commutators when b belongs to the new Campanato space Λ_β~θ(ρ) and 1/q = 1/p-mβ/n.     

A GENERALIZATION OF SIMPSON''''S RULE

Let TA(f)=integral form n= to 1/2(P_~n(x) + P_b~n(x))dx and let TM(f)=integral form n= to P_((+b)/2)~(n+1)(x)dx, where P_c~n denotes theTaylor polynomial to f at c of order n, where n is even. TA and TM are reach generalizations of theTrapezoidal rule and the midpoint rule, respectively. and are each exact for all polynomial of degree ≤n+1.We let L(f) = αTM(f) + (1-α)TA(f), where α =(2~(n+1)(n+1))/(2~(n+1)(n+1)+1), to obtain a numerical integrationrule L which is exact for all polynomials of degree≤n+3 (see Theorem l). The case n = 0 is just the classicolSimpson's rule. We analyze in some detail the case n=2, where our formulae appear to be new. By replacingP_(+b)/2)~(n+1)(x) by the Hermite cabic interpolant at a and b. we obtain some known formulae by a different ap-proach (see [1] and [2]). Finally we discuss some nonlinear numerical integration rules obtained by takingpiecewise polynomials of odd degree, each piece being the Taylor polynomial off at a and b. respectively. Ofcourse all of our formulae can be compounded over subintervals of [a, b].     

On Compact Hermitian Manifolds with Flat Gauduchon Connections

Given a Hermitian manifold(M~n, g), the Gauduchon connections are the one parameter family of Hermitian connections joining the Chern connection and the Bismut connection. We will call▽~s=(1-s/2)▽~c+s/2▽~b the s-Gauduchon connection of M, where ▽~c and ▽~b are respectively the Chern and Bismut connections. It is natural to ask when a compact Hermitian manifold could admit a flat s-Gauduchon connection. This is related to a question asked by Yau. The cases with s = 0(a flat Chern connection) or s = 2(a flat Bismut connection) are classified respectively by Boothby in the1950 s or by the authors in a recent joint work with Q. Wang. In this article, we observe that if either s ≥ 4 + 2×3~(1/2) ≈ 7.46 or s ≤ 4-2×3~(1/2) ≈ 0.54 and s ≠ 0, then g is K?hler. We also show that, when n = 2,g is always K?hler unless s = 2. Therefore non-K?hler compact Gauduchon flat surfaces are exactly isosceles Hopf surfaces.     

A REVERSE ORDER IMPLICIT Q-THEOREM AND THE ARNOLDI PROCESS

Let A be a real square matrix and VTAV = G be an upper Hessenberg matrix with positive subdiagonal entries, where V is an orthogonal matrix. Then the implicit Q-theorem states that once the first column of V is given then V and G are uniquely determined. In this paper, three results are established. First, it holds a reverse order implicit Q-theorem: once the last column of V is given, then V and G are uniquely determined too. Second, it is proved that for a Krylov subspace two formulations of the Arnoldi process are equivalent and in one to one correspondence. Finally, by the equivalence relation and the reverse order implicit Q-theorem, it is proved that for the Krylov subspace, if the last vector of vector sequence generated by the Arnoldi process is given, then the vector sequence and resulting Hessenberg matrix are uniquely determined.     

Generalized Semigroup on(V, H, a)

Let V and H be two Hilbert spaces satisfying the imbedding relation V\subset H. Let $[ - \mathscr{A}:V \to V''\]$ be the linear operator determined by a(u, v) = <\mathscr{A}u, v> for u, v\in V, where a(u, v) is a continuous sesquilinear form on V satisfying $a(u, u)+\lambda|u|_H^2\geq c||u||_V^2$ for u\in V and some \lambda \in R and c>0. In this paper it is proved that —\mathscr{A} is the generator of an analytic C_0-semigroup on V''. Furthermore, if b(u, v) is a continuous sesquilinear form on HxV and \mathscr{B}: H\rightarrow V, the linear operator determined by b(u, v) = (\mathscr{B}u, v) for u, v\in V, then —\mathscr{A}—mathscr{B} is also the generator of C_0-semigroup on V''. Also, similar results are proved on “inserted” spaces V_\theta(\theta \geq -1) which are determined by the spectrum system of \mathscr{A}.     

APPROXIMATION OF CONTINUOUS FUNCTIONS BY THE GENERALIZED BERNSTEIN-BEZIER POLYNOMIALS

§1. Introduction In [1], for any α>0, and a function φ defined on [0,1], Geng-Zhe Change defined the generalized Bernstein-Bezier polynomial ofφ as follows: B_(n, a)(φ, x) = sum from k=0 to n φ(k/n){f_(nk)~a(x)-f_(n,k+1)~a,(x)} (1.1)where f_(n, n+1) (x) =0 and f_(n, k)(x) = sum from j=k to n x~j(1-x)~(n-j) k=0,1,...,n. (1.2)are the Bezier base functions of degree n.Obviously, for any x ∈(0, 1), we have