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排序方式: 共有499条查询结果,搜索用时 15 毫秒
1.
《数学的实践与认识》2015,(10)
研究了一类上半平面中双周期函数的Hilbert边值逆问题.利用函数的对称扩张,将其转化为无穷直线上双周期Riemann边值问题,得到了问题的一般解及可解性定理. 相似文献
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讨论了自治系统接受的单参数Lie群组具有一种可解性的情况下求系统的一个首次积分的具体方法.对于n阶自治系统,给出相应参数的一组确定取值,求得系统首次积分;对于三阶自治系统,当系统接受的单参数Lie群组可解时,验证求得首次积分的条件一定成立. 相似文献
4.
给出了两个特殊的群类,即R={H|C_H(F(H))≤F(H)}和S={G|1≠K⊿G~((∞)),G~((∞))=KC_(G(∞))(K)},证明了他们都是Fitting类,这两个Fitting类都和单群理论有密切联系.各自都包含了一些很值得注意的群,对每个Fitting类给出了群G属于该Fitting类的一个充要条件. 相似文献
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引入弱SS-半置换子群的概念,介绍了弱SS-半置换子群的性质,结合有限群G的极小于群的弱SS-半置换性,并结合C-正规性来讨论有限群的超可解性及幂零性,得到了有限群超可解及幂零的若干充分或充要条件,同时推广了某些著名结果. 相似文献
6.
Eduardo lvarez-Miranda Alfredo Candia-Vjar Xu-jin CHEN Xiao-dong HU Bi LI 《应用数学学报(英文版)》2014,30(1):1-26
Given a connected graph G=(V,E)with a nonnegative cost on each edge in E,a nonnegative prize at each vertex in V,and a target set V′V,the Prize Collecting Steiner Tree(PCST)problem is to find a tree T in G interconnecting all vertices of V′such that the total cost on edges in T minus the total prize at vertices in T is minimized.The PCST problem appears frequently in practice of operations research.While the problem is NP-hard in general,it is polynomial-time solvable when graphs G are restricted to series-parallel graphs.In this paper,we study the PCST problem with interval costs and prizes,where edge e could be included in T by paying cost xe∈[c e,c+e]while taking risk(c+e xe)/(c+e c e)of malfunction at e,and vertex v could be asked for giving a prize yv∈[p v,p+v]for its inclusion in T while taking risk(yv p v)/(p+v p v)of refusal by v.We establish two risk models for the PCST problem with interval data.Under given budget upper bound on constructing tree T,one model aims at minimizing the maximum risk over edges and vertices in T and the other aims at minimizing the sum of risks over edges and vertices in T.We propose strongly polynomial-time algorithms solving these problems on series-parallel graphs to optimality.Our study shows that the risk models proposed have advantages over the existing robust optimization model,which often yields NP-hard problems even if the original optimization problems are polynomial-time solvable. 相似文献
7.
We study the quasi-exactly solvable problems in relativistic quantum mechanics. We consider the problems for the two-dimensional Klein-Gordon and Dirac equations with equal vector and scalar potentials, and try to find the general form of the quasi-exactly solvable potential. After obtaining the general form of the potential, we present several examples to give the specific forms. In the examples, we show for special parameters the harmonic potential plus Coulomb potential, Killingbeck potential and a quartic potential plus Cornell potential are quasi-exactly solvable potentials. 相似文献
8.
张四保 《数学的实践与认识》2016,(8):287-291
讨论了三类包含Euler函数的方程x-ψ(x)=2~(ω(x)),x-ψ(ψ(x))=2~(ω(x))与ψ(x~k)=2~(ω(x~k))的可解性,利用初等方法给出这三类方程的所有正整数解,其中ψ(x)为Euler函数,ω(x)为x的相异素因子个数. 相似文献
9.
Based on Wielandt’s criterion for subnormality of subgroups in finite groups, we study 2-maximal subgroups of finite groups and present another subnormality criterion in finite solvable groups. 相似文献
10.
Vesselin G. Gueorguiev 《原子核物理评论》2017,34(1):105-109
讨论了核结构模型中两体以上相互作用的可能形式。首先以基于手征微扰论并适于描述轻核的三体接触型相互作用为例,讨论了能合理描述3H 和3He 结合能的三核子接触型相互作用相关的两个低能有效耦合参数cD 和cE间的关系并通过4He 结合能给出了相应的物理参数区。其次通过Okubo-Lee-Suzuzki 有效相互作用方法对核多体问题在有限模型空间的求解,论证了A-体相互作用项。最后利用包含了A-体推广对力的可解模型对重核的同位素长链进行了分析。以132Sn 为核芯,通过对Sn 同位素链的计算揭示了推广对力参数G(A) 与模型价核子空间维数dim(A) 间的显著关系:G(A)=259.436 dim(A)-0.9985。这些分析结果说明,有必要对核中经手征微扰论或其它唯象理论所得到的NNN-,NNNN-,及A-体相互作用作进一步的研究。We discuss modeling of nuclear structure beyond the 2-body interaction paradigm. Our first example is related to the need of three nucleon contact interaction terms suggested by chiral perturbation theory. The relationship of the two low-energy effective coupling parameters for the relevant three nucleon contact interaction terms cD and cE that reproduce the binding energy of 3H and 3He has been emphasized and the physically relevant parameter region has been ilustrated using the binding energy of 4He. Further justification of A-body interaction terms is outlined based on the Okubo-Lee-Suzuki effective interaction method used in solving the nuclear many-body problem within a finite model space. The third example we use is an exactly solvable A-body extended paring interaction applied to heavy nuclei with a long isotopic chain; in particular using 132Sn as closed core system illustrates a remarkable relationship between the extended pairing strength G(A) and the size of the valence space dim(A) for the members of the Sn-isotope chain: G(A)=αdim(A)-β with α=259.436 and β =0.9985 which is actually a one parameter expression since β is practically 1. These three cases present evidence for the need of better understanding of the NNN-, NNNN-, and A-body interactions in nuclei either derived from ChPT or from a phenomenological considerations. 相似文献