一类有限p-群的因子分解数（英文）

Let p be a prime number and f_2(G) be the number of factorizations G = AB of the group G, where A, B are subgroups of G. Let G be a class of finite p-groups as follows,G = a, b | a~(p~n)= b~(p~m)= 1, a~b= a~(p~(n-1)+1), where n m ≥ 1. In this article, the factorization number f_2(G) of G is computed, improving the results of Saeedi and Farrokhi in [5].     

A note on the existence of fractional f-factors in random graphs

Let G=Gn,p be a binomial random graph with n vertices and edge probability p=p(n),and f be a nonnegative integer-valued function defined on V(G) such that 0a≤f(x)≤bnp-2np ㏒n for every x ∈V(G). An fractional f-indicator function is an function h that assigns to each edge of a graph G a number h(e) in [0,1] so that for each vertex x,we have dh G(x)=f(x),where dh G(x) = x∈e h(e) is the fractional degree of x in G. Set Eh = {e:e ∈E(G) and h(e)=0}.If Gh is a spanning subgraph of G such that E(Gh)=Eh,then Gh is called an fractional f-factor of G. In this paper,we prove that for any binomial random graph Gn,p with p≥n-23,almost surely Gn,p contains an fractional f-factor.     

The Entire Coloring of Series-Parallel Graphs

The entire chromatic number X_(vef)(G) of a plane graph G is the minimal number of colors needed for coloring vertices, edges and faces of G such that no two adjacent or incident elements are of the same color. Let G be a series-parallel plane graph, that is, a plane graph which contains no subgraphs homeomorphic to K_(4-) It is proved in this paper that X_(vef)(G)≤max{8, △(G) 2} and X_(vef)(G)=△ 1 if G is 2-connected and △(G)≥6.     

The Asymptotically Optimal Empirical Bayes Estimation about a Class of Uniform Distribution

In this note, we propose a squared error loss empirical Bayes estimator of θ based on past experiences and a present observation X which has conditional distribution. U(θ, cθ+b), where b is an arbitary constant when c>1; b>c when c=1, θ∈Ω=(-b/c-1,∞). When unkown prior G(θ) of θ belongs to the family {G:integral from Ω (θ~2dG(θ)<∞)}, our estimator is asymptotically optimal (see [1]). Let K(x) and k(x) be marginal distribution and density of r. v. X. It is easily seen that     

Quasi-periodic solutions of a semilinear Li(?)nard equation at resonance

We are concerned with the existence of quasi-periodic solutions for the follow- ing equation x″ F_x(x,t)x′ ω~2x φ(x,t)=0, where F and φare smooth functions and 2π-periodic in t,ω>0 is a constant.Under some assumptions on the parities of F and φ,we show that the Dancer's function,which is used to study the existence of periodic solutions,also plays a role for the existence of quasi-periodic solutions and the Lagrangian stability (i.e.all solutions are bounded).     

Liouville type theorems for Schrdinger systems

We study positive solutions to the following higher order Schr¨odinger system with Dirichlet boundary conditions on a half space:(-△)α2 u(x)=uβ1(x)vγ1(x),in Rn+,(-)α2 v(x)=uβ2(x)vγ2(x),in Rn+,u=uxn==α2-1uxnα2-1=0,onRn+,v=vxn==α2-1vxnα2-1=0,onRn+,(0.1)whereαis any even number between 0 and n.This PDE system is closely related to the integral system u(x)=Rn+G(x,y)uβ1(y)vγ1(y)dy,v(x)=Rn+G(x,y)uβ2(y)vγ2(y)dy,(0.2)where G is the corresponding Green’s function on the half space.More precisely,we show that every solution to(0.2)satisfies(0.1),and we believe that the converse is also true.We establish a Liouville type theorem—the non-existence of positive solutions to(0.2)under a very weak condition that u and v are only locally integrable.Some new ideas are involved in the proof,which can be applied to a system of more equations.     

Some Notes on a Minimization Problem

Let X[a,b] be a compact set containing at least n+1 points and Kan n-dimensional Haar subspace in c[a,b]. Let F(x,y) be a nonnegativefunction, defined on X×(-∞,∞), satisfying ‖F(·,p)‖<∞ with the L_∞norm forsome∈K, where F(x,p)≡F(x,p(x)). The minimization problem discussed in this paper is to find an elementp∈K such that ‖F(·,p)‖=inf ‖F(·,q)‖, such an element p(if any) is saidto be a minimum to F in K~(q∈K). The author in [1,2] studied this problem and has given the main theoremsin the Cbebyshev theory under the following assumptions: (A) lim F(x,y)=∞, x∈X; (B) lim F(x,u)=F(x,y), x∈X,y; (C)lim F(u,υ)=F(x,y),x∈X,y; (D) For each x∈X there existtwo real numbers f~-(x) and f~+(x),f~-(x)f~+(x). such that F(x,y) is strictlydecreasing with respect to y on (-∞,f~-(x)] and strictly increasing on [f~+(x),∞), and F(x,y)=F(x):=inf F(x,υ) on [f~-(x),f~+(x)]. Denote f_1(x)=inf{y:F(x,y)‖F~*‖},f_2(x)=sup{y:F(x,) ‖F‖},f_1(x)=lim f_1(u),f_2(x)=lim f_2(u), G=(q∈K: f_1qf_2}.For pεK set X_p={     

Integral closure of a quartic extension

Let R be a Noetherian unique factorization domain such that 2 and 3 are units,and let A=R[α]be a quartic extension over R by adding a rootαof an irreducible quartic polynomial p(z)=z4+az2+bz+c over R.We will compute explicitly the integral closure of A in its fraction field,which is based on a proper factorization of the coefficients and the algebraic invariants of p(z).In fact,we get the factorization by resolving the singularities of a plane curve defined by z4+a(x)z2+b(x)z+c(x)=0.The integral closure is expressed as a syzygy module and the syzygy equations are given explicitly.We compute also the ramifications of the integral closure over R.     

ON NEVANLINNA DIRECTIONS OF ALGEBROID FUNCTIONS

In this paper, a notation δχ(ω) is derived from the counting function Nχ(r,w) of branch points of algebriod functions. With this notation, the authors give the definition of the Nevanlinna direction for algebriod functions and discuss its existence in certain condition. By this notation the authors also obtain the numbers of exceptional value of the Julia direction and Borel direction of algebriod functions are not more than 2 [δχ(ω)],here [x] implies an maximum integer number which does not exceed x.     

具分段常变元的时滞微分方程的振动性

The delay differential equation with piecewise constant argument x′(t)+a(t)x(t)+b(t)x([t-k])=0 is considered,where a(t) and b(t) are continuous functions on [-k,∞),b(t)≥0,k is a positive integer and [·] denotes the greatest integer function.Some new oscillation and nonoscillation conditions are obtained.