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1.
强连通有向图D称为极小的,若在D中删去任意一条弧,则所得的有向图不是强连通的.讨论了极小强连通有向图的耳朵分解的一些性质,构造了非平面极小强连通有向图的例子, 证明了极小强连通图的点色数至多是3,并且当极小强连通图的耳朵分解中每个耳朵的长度不小于4时,它有两个不相交的准核.最后确定了给定顶点数的极小强连通有向图的弧数的界,刻画了相应的极图.  相似文献   

2.
有向图D称为超级边连通的,若每个最小边割都是由发自某顶点的边组成,或由发至某顶点的边组成.没有零度点的有向图D的倒数度为R(D)=∑veV(D)(1/d(v)).笔者给出有向图的超级边连通性的倒数度条件.不同的例子将说明这些条件是最好可能的.  相似文献   

3.
一个双色有向图D是本原的,如果存在非负整数h和k,h+k〉0,使得D的每对顶点(i,j),都存在从i到j的(h,k)-途径,并称h+k的最小值为双色有向图D的本原指数.文章给出了一类双色有向图的本原指数集,并对其极图进行刻画.  相似文献   

4.
一类特殊双色有向图的本原指数集   总被引:2,自引:0,他引:2  
一个双色有向图D是本原的,如果存在非负整数h和k,h+k〉0,使得D的每对顶点(i,j),都存在从i到j的(h,k)-一途径。此时,把h+k的最小值定义为双色有向图D的本原指数,文章给出一类特殊双色有向图的本原指数集,并对极图进行了刻化。  相似文献   

5.
在无向图G中,对于正整数k≥1,图G的一个k元控制集D是顶点集V(G)的一个子集,并且使得G中的每一个顶点至少被D中k个点控制.文章给出了在无向de Bruijn图和Kautz图中最小k元控制集的基数.  相似文献   

6.
一个双色有向图D是本原的,如果存在非负整数h和k,h+k>0,使得D的每对顶点(i,j),都存在从i到j的(h,k)-途径.对所有的h和k,h+k的最小值定义为双色有向图D的本原指数.给出了一类双色有向图的本原指数集,并对极图进行了刻化.  相似文献   

7.
一个双色有向图D是本原的,如果存在非负整数h和k,且h+k〉0,使得D中的每对顶点(i,j),都存在从i到j的(h,k)途径.将k+k的最小值定义为双色有向图D的本原指数.给出了一类双色有向图的本原条件和指数上界,并对极图进行了刻画.  相似文献   

8.
无限维拓扑学是拓扑学的一个新的领域,文章介绍了有关ANR和AR相关的性质,并且给出以下几个命题:1)ANR的有限积是ANR.2)每一个可缩空间是道路连通的.3)X上的每一个单位分解是可数集.4)X={0,1}是ANR,不是AR.5)X是AR→X是ANR.6)AR的收缩核是AR,ANR的邻域的收缩核是ANR.并且给予了证明.  相似文献   

9.
图G的最长路的阶称为环游阶,记为τ(G)。顶点集V(G)的子集S称为图G的Pn-核,如果满足τ(G[S])≤n-1且V(G)-S的每一个顶点v都与G[S]中阶为n-1路的端顶点相连。把顶点集V(G)剖分成A,B两部分,使得τ(G[A])≤a和τ(G[B])≤b,此剖分称为图G的一个(a,b)-剖分。本文证明了对于n≤3g/2-1的正整数,任意围长为g的图都有一个Pn+1-核。并且还得到,如果τ(G)=a+b,其中1≤a≤b,图G的围长g≥2/3(a+1),那么G有一个(a,b)-剖分。  相似文献   

10.
设D是n(≥2)阶强连通有向图.猜想:如果D中每一对不相邻且有公共外邻或公共内邻的顶点x,y都有d(x) d(y)≥2n-1,那么D是Hamilton有向图.文章证明了当n≥7时,若D中每一个不相邻且有公共外邻或公共内邻的顶点x,y都有d(x) d(y)≥(5n)/2-5,则D是Hamilton有向图.当3≤n≤6时,存在非Hamilton有向图D满足D中每一对不相邻且有公共外邻或公共内邻的顶点x,y都有d(x) d(y)≥(5n)/2-5.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

20.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

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