构造向量解题

文 [1 ]举例说明了平面向量在中学数学中的广泛应用 .作为文 [1 ]的补充 ,本文再举几例 ,说明构造向量 ,利用向量的内积在中学数学其它一些方面的应用 .1　求值例 1　设 a,b,c,x,y,z均为实数 ,且a2 b2 c2 =2 5,x2 y2 z2 =3 6,ax by cz =3 0 .求 a b cx y z的值 .解　由题设条件 ,考虑构造向量 p=(6a,6b) ,q=(5x,5y) .由 (p.q) 2 ≤ |p|2 |q|2 ,有 90 0 (ax by) 2 ≤ 90 0 (a2 b2 ) (x2 y2 ) ,即　 (3 0 - cz) 2 ≤ (2 5- c2 ) (3 6- z2 ) ,变形整理得　 (5z - 6c) 2≤ 0 ,∴　 5z =6c.同理　 5x =6a,　 5y =6b.∴…     

涉及例外函数与分担函数的正规族

设F是区域D内的一族亚纯函数,a(z),b(z),c(z)是区域D内三个判别的亚纯函数,其中一个可以恒为无穷,且对于任意z∈D,a(z)≠b(z),a(z)≠c(z),b(z)≠c(z),S={a(z),b(z),c(z)}.若对于任意两个函数f,g∈F,f与g在D内分担集合S,则F在D内正规.该结果推广了著名的Montel正规定则.     

Multiple solutions for weighted nonlinear elliptic system involving critical exponents

In this paper,by using the idea of category,we investigate how the shape of the graph of h(x)affects the number of positive solutions to the following weighted nonlinear elliptic system:-div(|x|-2au)-μu|x|2(a+1)=αα+βh(x)|u|α-2|v|βu|x|b2*(a,b)+λK1(x)|u|q-2u,in,-div(|x|-2av)-μv|x|2(a+1)=βα+βh(x)|u|α|v|β-2v|x|b2*(a,b)+σK2(x)|v|q-2v,in,u=v=0,on,where 0∈is a smooth bounded domain in RN(N 3),λ,σ0 are parameters,0μμa(N-2-2a2)2;h(x),K1(x)and K2(x)are positive continuous functions in,1 q2,α,β1 andα+β=2*(a,b)(2*(a,b)2N N-2(1+a-b),is critical Sobolev-Hardy exponent).We prove that the system has at least k nontrivial nonnegative solutions when the pair of the parameters(λ,σ)belongs to a certain subset of R2.     

涉及导数的一类全纯函数的正规族

主要使用Zalcman引理来研究全纯函数的正规族,得到了如下的结论:令F为|z|<1内的一族全纯函数,n是一个正整数,a,b是两个复数且满足a≠0,∞,b≠∞.若F满足:Ⅰ)■f∈F,如f有零点,则f的零点重级大于等于3;和Ⅱ)当n≥4时,对F的每一对函数G和H,G″-aG~(n,)与H″-aH~n分担b.则F在|z|<1内正规.     

β级星像函数类和凸像函数类的扩展问题

本文利用文[2,3]的引理和算子L(a,c)f(z)的一些性质.结合Hadamard乘积,研究了算子L(a,c)f(z),获得了L(a,c)f(z)∈S*(β)和L(a,c)f(z)∈K(β)的充分条件,推广了文[2,3]的相关结论.     

Some Generalization for an Operator Which Preserving Inequalities Between Polynomials

For a polynomial p(z) of degree n which has no zeros in |z| 1, Dewan et al.,(K. K. Dewan and Sunil Hans, Generalization of certain well known polynomial inequalities, J. Math. Anal. Appl., 363(2010), 38–41) established zp′(z) +nβ2p(z) ≤n2{( β2 + 1+β2)max|z|=1|p(z)|-( 1+β2- β2)min|z|=1|p(z)|},for any complex number β with |β|≤ 1 and |z| = 1. In this paper we consider the operator B, which carries a polynomial p(z) into B[ p(z)] := λ0p(z) + λ1(nz2)p′(z)1!+ λ2(nz2)2 p′′(z)2!,where λ0, λ1, and λ2are such that all the zeros of u(z) = λ0+c(n,1)λ1z+c(n,2)λ2z2lie in the half plane |z| ≤ |z-n/2|. By using the operator B, we present a generalization of result of Dewan. Our result generalizes certain well-known polynomial inequalities.     

Existence of multiple solutions for a fractional p-Laplacian system with concave-convex term

In this article, we study the existence of multiple solutions for the following system driven by a nonlocal integro-differential operator with zero Dirichlet boundary conditions{(-?)_p~su = a(x)|u|~(q-2) u +2α/α + βc(x)|u|~(α-2) u|v|~β, in ?,(-?)_p~sv = b(x)|v|~(q-2) v +2β/α + βc(x)|u|α|v|~(β-2) v, in ?,u = v = 0, in Rn\?,(0.1) where Ω is a smooth bounded domain in Rn, n ps with s ∈(0,1) fixed, a(x), b(x), c(x) ≥ 0 and a(x),b(x),c(x) ∈L∞(Ω), 1 q p and α,β 1 satisfy pα + βp*,p* =np/n-ps.By Nehari manifold and fibering maps with proper conditions, we obtain the multiplicity of solutions to problem(0.1).?????     

带解析系数的二维奇异积分方程

本文我们研究二维奇异积分方程和它的共轭奇异积分方程这里G表示单位圆|z|<1,a(z),b(z),c(z)是G内的解析函数,我们不但建立了解的表达式,而且找出了这些方程可解的必要和充分条件。 我们研究奇异积分方程这里G是复平面z=x+iy上的单位圆:|z|<1.a(z),b(z),c(z)是G内的解析函数,属于C~1((?))。复值函数f和φ分别是L_p((?)),p>2中的已知和未知函数,同时还研究和它共轭的非齐次积分方程这里g和ψ分别是共轭空间L_q((?)),1/p+1/q=1中的已知和未知的复值函数,A和A~*由关系式Re(Aφ,ψ)=Re(φ,A~*ψ)相联系。     

与例外函数和分担函数相关的亚纯函数的正规族

设F为区域D内的一族亚纯函数,对于每个f∈F,f的所有极点重数至少是2,a(z)和b(z)为两个在D内满足a(z)■b(z)的全纯函数.若对于每个f∈F,f(z)≠a(z)和f(z)≠b(z),则F在D内正规.这个结果改进了经典的Montel定则.此外,我们也讨论了亚纯函数族中每个函数与其导函数分担两个全纯函数的正规性.     

一类带Sobolev-Hardy指数的椭圆型方程组无穷多球对称解的存在性

考虑了一类带Sobolev-Hardy指数的椭圆型方程组{-Δu-μu/|x|2=α/α+β|μ|α-2u|v|β/|x|s+σp/p+q|u|p-2u|v|q,x∈B,-Δu-μu/|x|2=β/α+β|μ|α|v|β-2v/|x|s+σp/p+q|u|p|v|q-2,x∈B,其中0≤μμ,-4,μ=((N-2)~2)/4,σ0,0≤s2,N6+s,α+β=2~*(s)=(2(N-s))/(N-2),p,q≥1,2≤p+q2~*(s),B■R~N为以原点为心的一个开球.利用逼近方法及喷泉定理,得到了上述方程组无穷多个球对称解的存在性.     

Additive summable processes and their stochastic integral

We define and study a class of summable processes, called additive summable processes, that is larger than the class used by Dinculeanu and Brooks [D-B]. We relax the definition of a summable processesX:Ω×ℝ₊→E⊂L(F, G) by asking for the associated measureI _X to have just an additive extension to the predictableσ-algebra ℘, such that each of the measures (I _X) _z , forz∈(L _G ^p )*, beingσ-additive, rather than having aσ-additive extension. We define a stochastic integral with respect to such a process and we prove several properties of the integral. After that we show that this class of summable processes contains all processesX:Ω×ℝ₊→E⊂L(F, G) with integrable semivariation ifc ₀ ∋G.     

Commutative rings whose zero-divisor graph is a proper refinement of a star graph

A graph is called a proper refinement of a star graph if it is a refinement of a star graph, but it is neither a star graph nor a complete graph. For a refinement of a star graph G with center c, let G _c ^* be the subgraph of G induced on the vertex set V (G)\ {c or end vertices adjacent to c}. In this paper, we study the isomorphic classification of some finite commutative local rings R by investigating their zero-divisor graphs G = Γ(R), which is a proper refinement of a star graph with exactly one center c. We determine all finite commutative local rings R such that G _c ^* has at least two connected components. We prove that the diameter of the induced graph G _c ^* is two if Z(R)² ≠ {0}, Z(R)³ = {0} and G _c ^* is connected. We determine the structure of R which has two distinct nonadjacent vertices α, β ∈ Z(R)* \ {c} such that the ideal [N(α) ∩ N(β)]∪ {0} is generated by only one element of Z(R)*\{c}. We also completely determine the correspondence between commutative rings and finite complete graphs K _n with some end vertices adjacent to a single vertex of K _n .     

Large deviations and continuum limit in the 2D Ising model

Summary. We study the 2D Ising model in a rectangular box Λ _L of linear size O(L). We determine the exact asymptotic behaviour of the large deviations of the magnetization ∑ _t∈ΛL σ(t) when L→∞ for values of the parameters of the model corresponding to the phase coexistence region, where the order parameter m ^* is strictly positive. We study in particular boundary effects due to an arbitrary real-valued boundary magnetic field. Using the self-duality of the model a large part of the analysis consists in deriving properties of the covariance function <σ(0)σ(t)>, as |t|→∞, at dual values of the parameters of the model. To do this analysis we establish new results about the high-temperature representation of the model. These results are valid for dimensions D≥2 and up to the critical temperature. They give a complete non-perturbative exposition of the high-temperature representation. We then study the Gibbs measure conditioned by {|∑ _t∈ΛL σ(t) −m|Λ _L ||≤|Λ _L |L ^{− c} }, with 0<c<1/4 and −m ^*<m<m ^*. We construct the continuum limit of the model and describe the limit by the solutions of a variational problem of isoperimetric type. Received: 17 October 1996 / In revised form: 7 March 1997     

Intermittency and regularized Fredholm determinants

We consider real-analytic maps of the interval I=[0,1] which are expanding everywhere except for a neutral fixed point at 0. We show that on a certain function space the associated Perron-Frobenius operator ℳ has a continuous and residual spectrum contained in the line-segment σ _c =[0,1] and a point spectrum σ _p which has no points of accumulation outside 0 and 1. Furthermore, points in σ _p −{0,1} are eigenvalues of finite multiplicity. We construct a regularized Fredholm determinant d(λ) which has a holomorphic extension to λ∈ℂ−σ _c and can be analytically continued from each side of σ _c to an open neighborhood of σ _c −{0,1} (on different Riemann sheets). In ℂ−σ _c the zero-set of d(λ) is in one-to-one correspondence with the point spectrum of ℳ. Through the conformal transformation the function d∘λ(z) extends to a holomorphic function in a domain which contains the unit disc. Oblatum 10-X-1996 & 31-I-1998 / Published online: 14 October 1998     

A criterion of normality based on a single holomorphic function

Let F be a family of functions holomorphic on a domain D ⊂ ℂ Let k ≥ 2 be an integer and let h be a holomorphic function on D, all of whose zeros have multiplicity at most k −1, such that h(z) has no common zeros with any f ∈ F. Assume also that the following two conditions hold for every f ∈ F: (a) f(z) = 0 ⇒ f′(z) = h(z); and (b) f′(z) = h(z) ⇒ |f ^(k)(z)| ≤ c, where c is a constant. Then F is normal on D.     

Longest Paths and Longest Cycles in Graphs with Large Degree Sums

 Let p(G) and c(G) denote the number of vertices in a longest path and a longest cycle, respectively, of a finite, simple graph G. Define σ₄(G)=min{d(x ₁)+d(x ₂)+ d(x ₃)+d(x ₄) | {x ₁,…,x ₄} is independent in G}. In this paper, the difference p(G)−c(G) is considered for 2-connected graphs G with σ₄(G)≥|V(G)|+3. Among others, we show that p(G)−c(G)≤2 or every longest path in G is a dominating path. Received: August 28, 2000 Final version received: May 23, 2002     

Connected Domination Number of a Graph and its Complement

A set S of vertices in a graph G is a connected dominating set if every vertex not in S is adjacent to some vertex in S and the subgraph induced by S is connected. The connected domination number γ _c (G) is the minimum size of such a set. Let d^*(G)=min{d(G),d([`(G)])}{\delta^*(G)={\rm min}\{\delta(G),\delta({\overline{G}})\}} , where [`(G)]{{\overline{G}}} is the complement of G and δ(G) is the minimum vertex degree. We prove that when G and [`(G)]{{\overline{G}}} are both connected, g<sub>c</sub>(G)+g<sub>c</sub>([`(G)]) ￡ d^*(G)+4-(g_c(G)-3)(g_c([`(G)])-3){{\gamma_c}(G)+{\gamma_c}({\overline{G}})\le \delta^*(G)+4-({\gamma_c}(G)-3)({\gamma_c}({\overline{G}})-3)} . As a corollary, g<sub>c</sub>(G)+g<sub>c</sub>([`(G)]) ￡ \frac3n4{{\gamma_c}(G)+{\gamma_c}({\overline{G}})\le \frac{3n}{4}} when δ*(G) ≥ 3 and n ≥ 14, where G has n vertices. We also prove that g_c(G)+g_c([`(G)]) ￡ d<sup>*</sup>(G)+2{{\gamma_c}(G)+{\gamma_c}({\overline{G}})\le \delta^*(G)+2} when g<sub>c</sub>(G),g<sub>c</sub>([`(G)]) 3 4{{\gamma_c}(G),{\gamma_c}({\overline{G}})\ge 4} . This bound is sharp when δ*(G) = 6, and equality can only hold when δ*(G) = 6. Finally, we prove that g_c(G)g_c([`(G)]) ￡ 2n-4{{\gamma_c}(G){\gamma_c}({\overline{G}})\le 2n-4} when n ≥ 7, with equality only for paths and cycles.     

Differential subordinations concerning starlike functions

Denote byS ^* (⌕), (0≤⌕<1), the family consisting of functionsf(z)=z+a ₂z²+...+a_nzⁿ+... that are analytic and starlike of order ⌕, in the unit disc ⋎z⋎<1. In the present article among other things, with very simple conditions on μ, ⌕ andh(z) we prove the f’(z) (f(z)/z)^μ−1<h(z) implies f∈S^*(⌕). Our results in this direction then admit new applications in the study of univalent functions. In many cases these results considerably extend the earlier works of Miller and Mocanu [6] and others.     

On the iteration of holomorphic self-maps of ℂ*

Letf be a holomorphic self-map of the punctured plane ℂ^*=ℂ\{0} with essentially singular points 0 and ∞. In this note, we discuss the setsI ₀(f)={z ∈ ℂ^*:f ⁿ (z) → 0,n → ∞} andI _∞(f)={z ∈ ℂ^*:f ⁿ (z) → 0,n → ∞}. We try to find the relation betweenI ₀(f),I _∞(t) andJ(f). It is proved that both the boundary ofI ₀(f) and the boundary ofI _∞)f) equal toJ(f),I ₀(f) ∩J(f) ≠ θ andI _∞(f) ∩J(f) ≠ θ. As a consequence of these results, we find bothI ₀(f) andI _∞(f) are not doubly-bounded. Supported by the National Natural Science Foundation of China