综合题新编选登

题 8 8 　已知数列 {an},{bn}且a1=b1=1,an + 1=an+ 3bn,bn + 1=an+bn,记xn =anbn.1)求xn + 1与xn 的关系式 .2 )判断数列 {|xn - 3| }的单调性 .3)求数列 {xn}的极限值 .4 )求证 :|x1- 3| + |x2 - 3| +… +|xn - 3| <3+ 1.解　 1)xn + 1=an + 1bn + 1=an+ 3bnan +bn=anbn+ 3anbn+ 1=xn + 3xn + 1,其中x1=a1b1=1.2 )xn + 1- 3=xn+ 3xn+ 1- 3=( 1- 3) (xn- 3)1+xn.∵x1=1,xn + 1=xn + 3xn + 1,∴xn >0 .∴ |xn + 1- 3| =3- 11+xn|xn - 3|<( 3- 1) |xn - 3|<|xn - 3| .　 {|xn - 3| }为递减数列 .3)由 2 )知 :n >1时 ,0 <|xn - 3| <( 3- 1) |x…     

扰动压缩条件的点列收敛性问题

研究完备度量空间X中满足ρ(xn,xn+1)≤Lρ(xn-1,xn)+εn的点列{xn}收敛性问题,其中L∈(0,1)为常数,εn非负是无穷小量称为扰动.文中的主要结论是:点列{xn}的收敛性由扰动εn决定,即当幂级数sum from n=1 to ∞εnxn的收敛半径R>1/L时,点列{xn}收敛.特别地,当R>1时,点列收敛;而R=1时,{xn}敛散性不能确定.     

三步投影算法的收敛性及其在变分不等式组中的应用

First a general model for a three-step projection method is introduced, and second it has been applied to the approximation solvability of a system of nonlinear variational inequality problems in a Hilbert space setting. Let H be a real Hilbert space and K be a nonempty closed convex subset of H. For arbitrarily chosen initial points x0, y0, z0 ∈ K,compute sequences xn, yxn, zxn such that { xn+1=(1-αn-rn)xn+αxPk[yn-ρTyn]+rnun,yn=(1-β-δn)xn+βnPk[zn-ηTxn]+δnun,zn=(1-an-λn)xn+akPk[xn-γTxn]+λnwn.For η, ρ,γ>0 are constants,{αn}, {βn}, {an}, {rn}, {δn}, {λn} C [0,1], {un}, {vn}, {wn} are sequences in K, and 0≤n + rn ≤ 1,0 ≤βn + δn ≤ 1,0 ≤ an + λn ≤ 1,(A)n ≥ 0, where T : K → H is a nonlinear mapping onto K. At last three-step models are applied to some variational inequality problems.     

￠—半压缩算子和￠—强增殖算子方程的迭代

设E是任意实Banach空间,K是E的非空闭凸子集,T：K→K是一致连续￠-半压缩映像且值域有界。设{an},{bn},{cn},{a'n},{b'n}和{c'n}是[0,1]中的序列且满足条件：Ⅰ）an bn cn=a'n b'n c'n=1,任意n≥0;Ⅱ）limbn=limb'n=limc'n=0;Ⅲ）∑n=0^∞bn=∞;Ⅳ）cn=o(bn).对任意给定的x0,u0,v0∈K,定义Ishikawa迭代{xn}如下：{xn 1=anxn bnTyn cnun,yn=a'nxn b'nTxn c'nvn(任意n≥0),其中{un}和{vn}是K中两个有界序列。则{xn}强收敛于T的唯一不动点。最后研究了￠-强增殖算子方程解的Ishikawa迭代收敛性。     

Banach空间中渐近伪压缩映射的黏滞近似不动点序列

首先给出了渐近伪压缩映射的黏滞近似不动点序列的新定义,继而证明了如下逼近定理:令K为实Banach空间E的非空闭凸有界子集,T:K→K为一致L-Lipschitz、具数列{εn}的一致渐近正则、具数列{kn}的渐近伪压缩映射.假设迭代序列{xn}定义为:x1∈K,对n≥1,xn+1:=λnθnf(xn)+[1-λn(1+θn)]xn+λnTnxn,其中{λn},{θn}(0,1)且满足一定条件,则:当n→∞时,‖xn-Txn‖→0.     

一类Hermite-Fejér插值算子的平均收敛(Ⅱ)

设X0=1,xn+1=-1,{xk}kn=1是n阶Jacobi多项式的零点,本文给出基于{xk)k=1 n+1 的Hermite-Fejer插值算子平均收敛的一些充要条件.     

Oscillatory behavior of solutions of general third order mixed neutral difference equations

The objective of this paper is to study the oscillatory and asymptotic properties of the general mixed type third order neutral difference equation of the form△(aαn△2(xn+ bnxn-τ1+ cnxn+τ2)) + qnx n+1-σ+ p1nxβn+1+= 0,σ2where {an}, {bn}, {cn}, {qn} and {pn} are positive real sequences, both α and β are ratios of odd positive integers, τ1, τ2, σ1 and σ2 are positive integers. We establish some sufficient conditions which ensure all solutions are either oscillatory or converge to zero.     

逐差累加是法宝,出神入化显奇巧

先给出一个简单的数列问题: 已知数列{an}的首项a1=1,an+1=an+1,求数列{an}的通项公式. 一方面,很明显an+1-an=1,故根据等差数列的定义可求得:an=n.     

Convergence analysis of iterative sequences for a pair of mappings in Banach spaces

Let C be a nonempty closed convex subset of a real Banach space E. Let S ： C→ C be a quasi-nonexpansive mapping, let T ： C→C be an asymptotically demicontractive and uniformly Lipschitzian mapping, and let F ：= {x ∈C ： Sx = x and Tx = x}≠Ф Let {xn}n≥0 be the sequence generated irom an arbitrary x0∈Cby xn＋i=（1-cn）Sxn＋cnT^nxn, n≥0.We prove the necessary and sufficient conditions for the strong convergence of the iterative sequence {xn} to an element of F. These extend and improve the recent results of Moore and Nnoli.     

局部Cauchy列和局部完备性的性质

利用完备化的方法,给出了局部凸分离空间（X,T）中序列{xn}是局部Cauchy列当且仅当存在单调增且趋于正无穷大的正实数列{an},使得min{an,am}（xn-xm）→0（m,n→∞）,并得到局部凸分离空间（X,T）是局部完备的当且仅当X中每个丁局部Cauchy列的绝对凸闭包是丁紧的,以及一些局部完备性的相关性质．     

Study of the blow-up of solutions of systems of equations of hydrodynamic type

Mathematical Notes - We study the initial boundary-value problem for three-dimensional systems of equations of pseudoparabolic type. The system is similar to the Oskolkov system, but differs from...     

Characterization of types of asymptotic discernibility of families of hypotheses

We give a characterization of the types of asymptotic discernibility of families of hypotheses in the case of hypothetical measures that are not, in general, mutually absolutely continuous. The case when the logarithm of the likelihood ratio admits an asymptotic expansion of the type of an expansion with local asymptotic normality is examined in detail. Examples are studied.Translated fromTeoriya Sluchainykh Protsessov, Vol. 15, pp. 64–71, 1987.     

Distribution of types of symmetry of tensors of high degree

The asymptotic distribution of tensors of degree N in symmetry types is studied in this paper.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 155, pp. 181–186, 1986.     

Axiomatizability of reducts of algebras of relations

In this paper, we prove that any subreduct of the class of representable relation algebras whose similarity type includes intersection, relation composition and converse is a non-finitely axiomatizable quasivariety and that its equational theory is not finitely based. We show the same result for subreducts of the class of representable cylindric algebras of dimension at least three whose similarity types include intersection and cylindrifications. A similar result is proved for subreducts of the class of representable sequential algebras. Received October 7, 1998; accepted in final form September 10, 1999.     

Lengths of periods of continued fractions of square roots of integers

Empirical study of the period’s length T of the continued fractions of $\sqrt{Q}$ (for growing integers Q) shows several strange asymptotical results, for instance, $T\leq C\sqrt{Q}\ln{Q}$ . These results show important differences between the statistics of the elements of the continued fractions of random real numbers and of square roots of random integers.