变换图G^--＋与G^-＋-的平面性

设G是一个简单图，G^--＋，G^-＋-是G的变换图.在这篇文章中，证明了对于给定的一个图G，（1）G^--＋是平面图当且仅当n≤3或G同构于2K1＋K2，K1＋K1，2，K1，3或K1＋C3；（2）G^-＋-是平面图当且仅当n≤4且G不同构于K4-e.     

两类几乎单群与斯坦诺4-设计

对两类几乎单群旗-传递作用于斯坦诺4-设计上情况进行了讨论. 得到了：设D=（X,B,I）是非平凡的斯坦诺4-设计,D的自同构群G旗-传递地作用在D上.若G是几乎单群,则Soc（G）不同构于单群HS（这里v=176）和CO3（这里v=276）.     

循环图的Laplace的谱半径

设G=（V,E）是一个简单的连通图;用A（G）,D（G）分别表示G的邻接矩阵和顶点的度对角矩阵,令L（G）=D（G）-A（G）表示G的拉普拉斯矩阵,设L（G）的特征值为μ1≤μ2……≤μn。其最大特征值称为图G的谱半径,记作μ=μ本文就循环图的拉普拉斯谱半径的下界给予讨论,我们得到了两个结论．     

四川乐山市高中1994届数学(理工农医类)第一次调研考试试题及解答

一、选择题：（每小题4分，共68分）（1的值是（C）(A)1/4(B)1/8(C)3/4(D)3/8（2）若A＝｛x│x2-2x-3＜0｝，B＝｛x│lg(x 1）＜1｝,则A∩B为（D）（A)｛x│x≤-1｝∪｛x│3≤x≤9｝（B）｛x｜－1＜x＜3}（C)｛x｜－1＜x＜9｝（D)｛x｜3≤x＜9｝（3）如图，长方体ABCD－A'B'C'D'中，BB’＝BC，直线A’C和直线BC’的位置关系是（C）（A）互相垂直的相交直线（B）不互相垂直的相交直线（C）互相垂直的异面直线（D）不互相垂直的异面直线（4）过点（l，2），且与原点距离最大的直线方程是(A)（A）x＋2y－5＝0（B）2x＋y－4＝0…     

2-(v,11,1)设计的非可解区传递自同构群

本文主要讨论了区传递的2-（v,k,1）设计的分类,证明了如下的定理：设G是2-（V,11,1）设计中的区传递、点本原但非旗传递自同构群．若G非可解,则G的基拄Soc（G）≠^2G2（q）．     

旗传递（v，k，3）-对称设计的自同构群。与它们的抛物子群

文章研究了（v,k,3）-对称设计D的分类;证明了如果群G是D的几乎单型的自同构群,即存在非交换单群X使得X≤G≤Aut（D）,那么X∩Ga不可能是X的抛物子群．     

广义Mycielskian图的超连通性

Mycielski引入了对于图G的一类新的变换图μ（G）,称为G的Mycielskian.这类变换图的推广是广义Mycielskian图μm（G）,m是正整数.如果每个最小点割（最小边割）孤立G的一个点,则称图G是超连通的或超-κ（超边连通的或超-λ）.证明结果显示：设G是连通图且｜V（G）｜≥3条件下,μm（G）是超-κ的充要条件是δ（G）＜（m＋1）κ（G）;μm（G）是超-λ的充要条件是G（≠）K2,即G不是一条边.     

θ-复形的图结构

给出了一类特殊拓扑空间一θ-复形和θ-复形的图的定义,然后讨论了日一复形的图结构,从而更加形象直观地描述了口一复形中顶点、开滤子与闭滤子之间的关系,并证明了结论：（1）设K是口一复形,G为其图,则对任意的中心滤子点U,有2≤dG（u）≤3;（2）设K是θ-复形,G为其图,则在G中不存在循环图;（3）设θ-复形K的图G为树,则在G中任意两个中心滤子点均由唯一的途径连接;（4）设u为中心滤子点,口为边滤子点或者顶点,则有d（u,v）=2m-1,m∈ω．     

四类平均数图解的进一步探究

问题 已知a，b都是正数，求证： 2/（1/a）＋1（1/b）≤√ab≤a＋b/2≤√（a^2＋b^2）/2,记为H≤G≤A≤Q，即：调和平均（H）≤几何平均（G）≤算术平均（A）≤平方根平均（Q）．这是高中数学第二册（上）中的一道习题，也是高中数学实验教材第五册第111页探究的一部分．本将给出两种非常直观的几何证法，并作进一步的引申．[第一段]     

笛卡尔积图Tn×Cm的交叉数

两个图G1和G2的笛卡尔积图G1×G2定义为如下的图：V（G1×G2）=V（G1）×V（G2）,E（G1×G2）={（u1,u2）（v1,v2）｜u1=v1且u2v2∈E（G2）,或者u2=v2且u1v1∈E（G1）}．图的交叉数是图论中的一个重要拓扑参数,而确定图的交叉数是一个完全胛一问题．本文确定了若干树Tn（n≤4）与圈Cm的笛卡尔积图的交叉数．     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

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?     

只要努力,不要后悔

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.     

浅谈移民问题

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.     

Sister Carrie, an Adherent of Desires

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.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.