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1.
关于图的代数连通度的注记   总被引:3,自引:1,他引:3  
n阶连通图G的代数连通度、点连通度和边连通度分别记作α(G) ,κ(G)和λ(G) .本文给出了当 2 κ(G) n- 2时 ,α(G) =κ(G)成立的充要条件 ,讨论了α(G)的代数重数以及相应于特征值α(G)的特征向量的性质 .最后给出了当 1 λ(G) n- 2时 ,α(G) =λ(G)的充要条件 .  相似文献   

2.
设G是简单图,用P(G,λ)表示图G的色多项式.令K(m,n,r)表示完全三部图。G=K(m,n,r)-A(|A|=2),3≤m≤n≤r.证明了若图Y使得P(Y,λ),则Y=K(m+α,n+β,r-(α+β))-S,其中α,β是整数,且|S|=e=(r-m)α+(r-n)β-2(α^2+αβ+β^2)≥0.且e=2时,G和Y同构,同时给出了α,β的范围。  相似文献   

3.
关于独立数上界的讨论   总被引:2,自引:0,他引:2  
在定义了简单图的特征矩阵和规范特征矩阵后,对特征矩阵进行分析,得到了简单图的独立数的一个上界:α(G)≤[(1+√4n^2-4n-8m+1)/2],并且针对非连通图对上界定理进行了改进,得到了更优的上界:α(G)≤(s∑i=1)[(1+√4n^2i-4ni-8mi+1)/2]。  相似文献   

4.
文章讨论了边连通简单图的独立数与上可嵌入性的关系,得到了下列结果:(1)设G是一个k-边连通简 单图(k=1,2),若α(G)≤k,则G是上可嵌入的;(2)设G是一个3-边连通简单图,若α(G)≤5,则G是上可嵌入 的。  相似文献   

5.
Everett和Borgatti引入了k-角色分配的概念.进一步,他们引入并研究了图G的k-角色可分配程度来表示图G可以在多大程度上进行k-角色分配,记作αk(G).他们还给出了k=2时的k-角色可分配程度α2(G)的下确界,并回答了什么时候α2(G)达到下确界.本文证明了k≥3时,αk(G)的下确界为0,并证明了当图G为G1,sk+1图且a(s+1)≠0(mod k+1)(a=2,3,4)时,αk(G)达到下确界;最后还刻画了能够(n-1)-角色分配的G1,sn图.  相似文献   

6.
给一个图G,XV(G),G[X]为G的X生成子图,r为正整数。定义α(X)=max{|S|}S是G[X]的顶点独立集},αk(X)=min{∑ki=1d(vi)|{v1,v2,…,vk}是G[X]的顶点独立集},NCk(X)=min{|Uki=1N(vi)|{v1,…,vk是G[x]的独点独立集}(k≥2).我们得到结论;对—任意的n阶2-连通图G(n≥3),xG,且α3(X)≥n+r≥n+2,则存在一个包含X的顶点数为min{|X|,[X]+NC,+2+e(n+r)(X)-α(X)}的圈,ε(i)=3〔1-3i〕-1-3i.该结论推广了H.J.Broersma在文献[1]中的结果.  相似文献   

7.
Everett和Borgatti引入了k-角色分配的概念。进一步,他们引入并研究了图G的k-角色可分配程度来表示图G可以在多大程度上进行k-角色分配,记作αk(G).他们还给出了k=2时的k-角色可分配程度α2 (G)的下确界,并回答了什么时候α2(G)达到下确界。本文证明了k≥3时,αk(G)的下确界为0,并证明了当图G为Gk+1l,s图且α(s+1)≠0(mod k+1)(a=2,3,4)时,αk(G)达到下确界;最后还刻画了能够(n-1)-角色分配的Gn1,s图。  相似文献   

8.
在有限群论中,我们常常通过研究一个有限群的自同构的性质,来认识这个有限群的性质,本文遵循这一方法,建立了以下的定理:定理:设G为有限群,G有一个自同构α,使得由α定义的集合I={a∈G|α(a)=a~(-1)}含有3/4|G|个元素的充要条件是:G是非阿贝尔的,且可写G=HK=KH,这里H、K均为G的指标为2的阿贝尔子群.其次,若群G满足上述条件则C(G)=H∩K,且  相似文献   

9.
Dirac定理指如果n个顶点的图G最小度至少为n/2,则G包含一个哈密尔顿圈. Bohman等引入了随机扰动图模型并证明了对任意正常数α和最小度至少为αn的图H,存在一个仅依赖于α的常数C使得对任意p≥C/n H∪Gn,p是几乎渐进肯定哈密尔顿的。本文考虑了随机扰动有向图模型,证明了对任意α=ω{(logn/n)1/4}和d∈{1, 2},一个最小度至少αn的n点有向图和随机d正则有向图是几乎渐进肯定泛圈的。更进一步,给出了一个在这种随机扰动有向图中构造任意长度有向圈的算法。  相似文献   

10.
4p阶内2-闭群的m-DCI-性   总被引:4,自引:1,他引:3  
C ay ley图的C I性是研究其同构问题的重要性质。考察一类内2-闭群G=〈a,b a2α=bp=1,-a 1ba=-b 1〉当α=2时的(弱)m-(D)C I-性,并证明G是3-DC I-群和弱5-C I-群。  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.
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   

19.
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   

20.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

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