共查询到20条相似文献，搜索用时 62 毫秒
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《钦州师专钦州教院学报》1995,9(3):52-55
设G是连通偶图，（X1，X2）是其顶点的二分类，|X1|=|X2|=n，δ（G）≥t≥3。证明了若任意u,v∈Xi蕴含|N(u)∪N(v)|≥n-（t-2），i=1,2，则当t=7时G是点泛圈偶图。 相似文献
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《钦州师专钦州教院学报》1997,12(2):67-72
设G是连通偶图，（X1，X2）是其顶点的二分类，|X1|=|X2|=n,δ（G）≥t≥3。证明了若任意,u,v∈Xi，蕴含|N(u)∪N（v)|≥n-（t-2），i＝1，2，则当t=8时G是点泛圈偶图。 相似文献
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链状四角系统的Randic指数 总被引：1，自引：0，他引：1
设G=（V,E）是一个图,其中顶点集V={v1,v2,…,vn}．G的Randid指数为：X（G）=∑vjvj∈E（G）1/√d（vi）d（vj）,其中d（v）表示顶点v的度．Randic指数是化学图论中常见且重要的一个拓扑指数．给出直链四角系统、锯齿链四角系统和转向细胞个数为1的链状四角系统的Randid指数． 相似文献
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设ap→b是无终点的3－γ－临界图G的一条Hamiltonian路,文［3］证明了当d（a,b）＝3时,G是Hamiltonian图．本文进一步研究3－γ－临界图的Hamilton性,得到如下结果：如果d（a,b）＝2且｜T｜＝1或T＝N（a）∩N＋（b）,则G是Hamiltonian图．这里,T＝V（G）－［N（a）∪N（b）∪｛a,b｝］． 相似文献
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《钦州师专钦州教院学报》1994,8(4):56-60
设G是连通偶图，（X1，X2）是其顶点的二分类，|X1|=|X2|=n,δ（G）≥t≥3。文中证明了：若任意u,v∈X，蕴含|N(u)∪N(v)| ≥n-[(t-1)/2],i=1,2，则G是偶点泛圈。 相似文献
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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． 相似文献
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《钦州师专钦州教院学报》1995,9(1):27-32
设G是连通偶图，（X1，X2）是其顶点的二分类，|X1|=|X2|=n,δ（G）≥t≥3，且对于X中的任意两点u和v，均有|N(u)∪N（v)|≥n-(t-2),i=1,2，文中对t≤6的情况，证明G是点圈偶图。 相似文献
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孙海娜 《海南师范学院学报》2005,18(2):97-98,103
H是线性交簇超图，｜E∩F｜：1（∨E、F∈H），记s=s（H）：min｜E｜，A：｜E∈H：｜E｜：s｜．若｜A｜〈s^2＋1，则m（H）≤A（[H]2）＋1；若｜A｜≥s^2＋1，则当s≤2时，m（H）≤△（[H]2）＋1；当s≥3时，m（H）≤△（[H]2）-2s． 相似文献
10.
设k和d是2个互素的正整数且k≥2d．G^dk是一个图,它的顶点集合为{0,1,…,k-1},边集合为{ij｜d≤｜i-j｜≤k-d,i,j=0,1,…,k-1}．图G的圆色数χc（G）定义为使得图G与G^dk同态的2个正整数k和d的最小比值k／d．研究了χc（G）和χc（G-v）之间的关系,对任意顶点v求出了χc（G^dk-v）的精确值,给出了具有对任意顶点χc（G-v）=χc（G）-1和其他特定性质的图类;并对图的圆色数的一些下界进行了探讨,给出了图的圆色数达到下界χc-1＋1／d的充要条件,这里χ和α分别是图G的点色数和独立数． 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
14.
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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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
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 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