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本文证明了下述结果:在适当条件下,若f∈ε_(?)～(?)(?),则g(f)(x)(s(f)(x),μ(f)(x))=∞,a,e.x∈R～(?)或g(f)(x)(s(f)(x),g_(?)～(?)(f)(x),μ(f)(x))<∞,a,e.x∈R～(?),在后一种情形,我们有g(f)(s(f),g_(?)～(?)(f),μ(f))∈ε_(?)～(?)(?)且‖g(f)‖(?)(‖s(f)(?)‖g_λ～(?)(f)‖(?)‖μ(f)‖(?))≤c‖f‖(?)其中C是不赖于f(x)的常数. 相似文献
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我们知道,在数值计算中的插值问题,实质上就是对某一基本空间X的一函数f(x)在一定约束条件下寻求逼近函数。本文试图从有限维子空间出发的逼近法,讨论一般的插值问题及其基函数的选取,从而对代数插值有一比较统一和本质的认识。一、插值问题的一般提法设X是线性函数空间,Y是X的n维线性子空间,u_i(i=1,2,…n)是定义在Y上的n个线性泛函。给定f(x)∈x 第一种插值问题的提法,求(x)∈Y使u_i(?)=y_i(i=1,2,…,n) 第二种插值问题的提法:求(?)(x)∈Y使U_i (?)=U_i(f)(i= 1,2,…,n) 二、问题的存在唯一性条件(以第二种提法提出) 定理1设Y是函数空间x的的-n维线性子空间,SPan{(?)_1,…(?)_n}是Y的某 相似文献
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杨荣先 《内江师范学院学报》1987,(Z1)
本文中均设(X,d)是一完备的度量空间,T,S是X→X的映象对,在O_T(X;0,∞)={x_a=T~(?)x}_(?)~∞=0(这里{x_(?)=T~(?)x}是迭代序列)称为T在x处生成轨道;记δ(O_r(x;0,∞))=Supd(T~(?)x,T~(?)x)称为0_r(x;0,∞)的直径.设对每一对x,y∈X,δ(O_r(x;0,∞)UO_(?)(y;0,∞))是有界的.称函数φ(t)满足如下条件叫做满足条件(φ_1):φ:[0,∞)→[0,∞)对t是不减和右连续的(即设{t_a}是非负值的单调减的序列,当t_a→t时,就有φ(t_(?))→φ(t))而且对每—t>0,有φ(t)0,φ~n(t)→0(n→∞),这里φ~n(t)表φ(t)的n次迭代函数.2°任一满足下面条件的非负实数列{t_(?)}_(?)~∞(?) 相似文献
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1=Gi(醑5 58蝉I一5 23 5—0 l u缒}5膏56晕)}懊1 l迥2I, I I I ^ l n -(领)桃花岭,杏花谷,曼曼曼垒缒I e鱼5 3 2 l(一s e s s缒l骝s.2)l逦3 3 2 3花果山的孩子 爱种树。 隔三步 ,、 I/、,^、 I,、 ‘ 0她5 I攀巡l咝1 l(.s—e 5 3逊f 5j 5—1)种桃树, 隔两步呀 种杏树。 x 羔 x x l x x x ‘。。。。。。…‘。。。’。’一(自)家家院里 种葡萄.2 2 3春风 (羔m Il!l x_j)吹(白:春风那个一 l吹呀)u u l兰圣苎兰业秘翠帘子 遮呀遮窗户。 (兰 兰 兰 兰遁5 5 3_2 2 I花辩舞(白:花辩那个 (X X X I X X) (X X X X :============一————… 相似文献
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三、CAT中对的估计(一)MLE(极大似然估计法)假设一个能力水平为θ的被试对n道项目X_1,X_2,…,X_n作答。θ的估计可以通过使(8)式所示的似然函数最大化的方式来得到。令(?)_n为此时所得的θ估计。显然(?)_n也是(9)式的极大似然估计。已知在一定的条件下,(?)_n符合渐进正态,其均值为θ,方差近似为I~(-1)_n((?)_n)。目前的CAT设计大多通过递归方式在被试回答一个新的项目之后得到最新的θ估计,并根据信息最大化法抽取下一个项目。 相似文献
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数学通报1981年第一期介绍了发表在《美国数学月刊》上的Rolle定理的两个新证明。正如编译者指出,Rolle定理的证明在许多数学分析教程中大多千篇一律,多年不变(几乎都要用最大(小)值定理)。《美国数学月刊》上的第一个证明是构造性的,第二个证明应用了两个现成的命题: (a)如果f(x)在闭区间[c,d]上连续,且f(c)=f(d),那么存在α,β∈[c,d]满足β-α=c-d/2,及f(α)=f(β); (b)如f(x)在某内点x可微,那么对于任意两个序列α_n,β_n满足α_n≤x≤β_n, 相似文献
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对于数学教学来说,反例的重要性是不言而喻的。我们将反例概念描述如下:设全集为X,A、B都是X的子集,如果有元素x∈X,x∈A时,x(?)B,则称x是集合包含关系A(?)B的一个反例。如果能举出A(?)B的一个反例,则立即可知A(?)B,所以A(?)B的一个反例就是A(?)B的一个特例。有此特例足以肯定A(?)B,也就是说,举出A(?)B的一个反例就是等价于证明 相似文献
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当曲面S用参数方程x=x(u,v),y=y(u,v),z=z(u,v)表示时,化第二型曲面积分为二重积分的计算公式原来为(?)s(x,y,z)dxdy=±(?)f[x(u,v),y(u,v),z(u,v)]c dudv,本文将它改进为(?)s(x,y,z)dxdy=±(?)f[x(u,v),y(u,v),z(u,v)]|c|dudv.使得积分号前的正负号的选择在某些情况下(例如对常见的教材和吉米多维奇著的数学分析习题集里的例题和习题)由难交易。 相似文献
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设 X 为一个 BCI-代数,N,H 为 X 的理想,A 为 X 的子代数,X/N 为通常意义下的商代数,C_0为 X/N 的常元,C_0(?)H(?)N(?)A.今A/N={C_x∈X/N|x∈A}本文主要证明了以下几个结果:i)X/N=X/H;ii)A/N(?)A/N;iii)当 A 还是 X 的理想时,A/N=A/N. 相似文献
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一、基础知识及语言运用 1.下列词语形、音、义全部正确的一项是( ) A.凋弊(di(?)o b(?)生活困苦)贫瘠(p(?)n j(?)土地不肥沃)偎倚(w(?)i y(?)亲切地靠着)恣(c(?))行无忌 B.昏庸(hun y(?)ng糊涂愚蠢)怃然(w(?) r(?)n失望的样子)荟萃(hu(?) cu(?)会集、聚集)如法炮(p(?)o)制 C.回溯(hu(?) shu(?)水往上流)沮丧(j(?) s(?)ng灰心失望)箴言(zh(?)n劝戒的话)过犹不及(力气超过了头还是达不到目标) D.游弋(y(?)u y(?)[兵船等]巡逻)侥幸(ji(?)o x(?)ng由于偶然的原因而得到成功或免去灾害)寥落(li(?)o lu(?)稀少;冷落)一暴(p(?))十寒 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献