微分多项式的例外集

设ｆ为任一超越整函数，为ｆ的任一微分多项式；本文证明了在满足｜ａ＿ｎ－ａ＿ｍ｜＞ε｜ａ＿ｎ｜（ｎ≠ｍ）和的无穷个圆盘的并集之外取任意有限非零复数无穷次。     

独立集的度和与图的哈密尔顿性

关于哈密尔顿连通图的一个基本结果是Ore给出的：设G是n阶图,若对于任意两个不相邻顶点u和v,有d(u) d(v)≥n 1,则G是哈密尔顿连通的．设G是一个图,对于任意u (?)V(G),令N(U)=∪_(u∈∪)N(u),d(U)=|N(U)|,称d(U)是U的度．本文利用独立集的度和得到如下结果：设s和t是正整数,G是(2s 2t 1)-连通n阶图．若对于任两个强不交独立集S,T,|S|=s,|T|=t,有d(S) d(T)≥n 1．则G是哈密尔顿连通的．同时也得到图的哈密尔顿性的其它相关结果．两个独立集S和T称为强不交的,如果S∪T也是独立集．     

两类树的独立集多项式的单峰性

研究了图的独立集多项式的单峰性,给出具有爪图结构的几类图的独立集多项式等价的无爪图,并在此基础上证明了两类具有爪图结构的树T(n,n+1,m)和T(I,i+1,k,j,j+1)的独立集多项式具有单峰性,从而为具有爪图结构的其它树的单峰性提供了一个证明方法.     

图的极大Tutte集的几个有效算法

图G=(V,E)的Tutte集定义为X■V(G)满足ω_o(G-X)一|X|=def(G).若不存在Tutte集Y■X,则称X为图G的极大Tutte集.通过找极大extreme集和D-图的极大独立集给出一般图G的找极大Tutte集的两个有效算法,并给出结论:X■V(G)是二部图G的极大Tutte集当且仅当X为二部图G的最小覆盖,从而得到找二部图G的极大Tutte集的一个有效算法.     

关于有效点集的闭性和连通性

本文的主要结果是，假设Ａ是局部凸空间里的紧的Ｆ一集，则Ａ的有效点集Ｅ（Ａ｜Ｃ）是闭集。需要提及的是，此结果中关于Ａ并没有作任何凸性的假设，如果对它再附加某种凸性假设条件时，则本文进一步证明了有效点集Ｅ（Ａ｜Ｃ）不但是闭集，而且还是连通集。     

AT-free图的配对控制集算法

本文给出了配对控制集在AT-free图的BFS-树上分布的结构性质．利用这些性质，我们给出了求解AT-free图类最小配对控制集的多项式时间算法．     

满足递推式紧集的Lipschitz等价性

设紧集U满足一个不交并递推式,U=(rU+(?))∪U_1.证明了若U_1与一个满足强分离条件的自相似集T Lipschitz等价,则U与T也是Lipschitz等价.并举例说明定理在自相似并集间的Lipschitz等价中的应用.     

关于广义Aluthge变换的谱性质的研究

设T∈H（H），T=U｜T｜是算子T的极分解，则定义T^λ=｜T｜^λU｜T｜^1-λ和T^λ（＊）=｜T＊｜^λU｜T＊｜^1-λ，（其中0〈λ〈1）分别为算子的广义Aluthge变换和广义＊-Aluthge变换．本文中主要研究了三者之间的几种谱的关系．同时，还证明了算子T满足修正的Weyl定理当且仅当弘满足修正的Weyl定理当且仅当T^λ（＊）满足修正的Weyl定理．最后证明了算子T满足a—Weyl定理当且仅当T^λ满足a—Weyl定理．     

关于满足强分离开集条件的自相似集的Hausdorff测度

设E是Rn中由相似压缩S1,S2,…,Sm所确定的满足开集条件的自相似集,其Hausdorff维数为s,其s-维Hausdorff测度记为Hs(E).利用部分估计原理得到了本文的主要结果:若E满足强分离开集条件,则在E中存在一个压缩拷贝串序列{Ui}和紧集U(|U|>0),使得Hs(U)等于|U|s,并且{Ui}按Hausdorff度量收敛到U,进而证明了由U可以构造一个数列,使得该数列正好收敛到Hs(E);另外,引入了自相似集的相似压缩不动点,得到了等式Hs(E∩U)=|U|s 成立的一个必要条件.     

子句集的神经网络归结

给出基于神经网络的归结方法。首先将子句集S表示为δ形式，并且用算子对(⊙， )引入两种类型的神经元；然后用这两种神经元构造子句集S的神经网络结构；而后给出基于子句集的神经网络的归结算法；最后证明了该算法的完备性，并用实例进行了验证。     

代数κ-拟-A类算子的Weyl定理

若T或T~*是无穷维可分的Hilbert空间H上的代数κ-拟-A类算子,则Weyl定理对任意的f∈H(σ(T))成立,其中H(σ(T))为σ(T)的开邻域上解析函数的全体.若T~*是代数κ-拟-A类算子,则a-Weyl定理对f(T)成立。还证明了若T或T~*是代数κ-拟-A类算子,则Weyl谱与本质近似点谱的谱映射定理对f(T)成立.     

关于连续线性算子广义预解集的某些结果

讨论了Banach 空间上连续线性算子$T$ 的广义预解集的相关结果,证明了:若$\lambda_0\in\rho_G(T),$ 当~$|\lambda-\lambda_0|<\gamma(T_{\lambda_0})$ 时,$\lambda\in\rho_G(T);$ 与~$\lambda\in\rho_G(T)$ 等价的条件:当~$T_n\to T, 0\in \rho_G(T_n),则~$0\in\rho_G(T);$ 以及$T$ 的柱心~$C_O(T)$ 在数量扰动下的不变性.     

The $L(3, 2, 1)$-Labeling on Bipartite Graphs

An $L(3, 2, 1)$-labeling of a graph $G$ is a function from the vertex set $V(G)$ to the set of all nonnegative integers such that $|f(u)−f(v)|≥3$ if $d_G(u, v)=1$, $|f(u)−f(v)|≥2$ if $d_G(u, v)=2$, and $|f(u)−f(v)|≥1$ if $d_G(u, v)=3$. The $L(3, 2, 1)$-labeling problem is to find the smallest number $λ_3(G)$ such that there exists an $L(3, 2, 1)$-labeling function with no label greater than it. This paper studies the problem for bipartite graphs. We obtain some bounds of $λ_3$ for bipartite graphs and its subclasses. Moreover, we provide a best possible condition for a tree $T$ such that $λ_3(T)$ attains the minimum value.     

Bounded VC-Dimension Implies a Fractional Helly Theorem

We prove that every set system of bounded VC-dimension has a fractional Helly property. More precisely, if the dual shatter function of a set system $\FF$ is bounded by $o(m^k)$, then $\FF$ has fractional Helly number $k$. This means that for every $\alpha>0$ there exists a $\beta>0$ such that if $F_1,F_2,\ldots,F_n\in\FF$ are sets with $\bigcap_{i\in I}F_i\neq\emptyset$ for at least $\alpha{n\choose k}$ sets $I\subseteq\{1,2,\ldots,n\}$ of size $k$, then there exists a point common to at least $\beta n$ of the $F_i$. This further implies a $(p,k)$-theorem: for every $\FF$ as above and every $p\geq k$ there exists $T$ such that if $\GG\subseteq\FF$ is a finite subfamily where among every $p$ sets, some $k$ intersect, then $\GG$ has a transversal of size $T$. The assumption about bounded dual shatter function applies, for example, to families of sets in $\Rd$ definable by a bounded number of polynomial inequalities of bounded degree; in this case we obtain fractional Helly number $d{+}1$.     

亚纯函数的导函数分担集合的唯一性

研究了两个亚纯函数的导函数分担两个值集的唯一性问题. 证明了对于集合$S$和$T$, 如果$\overline{E}_{f^{(k)}}(S)=\overline{E}_{g^{(k)}}(T)$, 则存在非零常数$A$, 使得$f^{(k)}=Ag^{{(k)}}$. 特别地, 当$k=0$时, 有$f=Ag$.     

On Jordan Biderivations of Triangular Matrix Rings

Let $R$ and $S$ be rings with identity, $M$ be a unitary $(R,S)$-bimodule and $T=\left(\begin{array}{cc}R & M \\ 0 & S\end{array}\right) $ be the upper triangular matrix ring determined by $R$, $S$ and $M$. In this paper we prove that under certain conditions a Jordan biderivation of an upper triangular matrix ring $T$ is a biderivation of $T$.     

两个$l^p(\Gamma)$型空间单位球面之间的1-Lipschitz映射的延拓($1

方习年 《数学研究及应用》2009,29(4):687-692

1-Triangle graphs and perfect neighborhood sets

A graph is called a 1-triangle if, for its every maximal independent set I, every edge of this graph with both endvertices not belonging to I is contained exactly in one triangle with a vertex of I. We obtain a characterization of 1-triangle graphs which implies a polynomial time recognition algorithm. Computational complexity is establishedwithin the class of 1-triangle graphs for a range of graph-theoretical parameters related to independence and domination. In particular, NP-completeness is established for the minimum perfect neighborhood set problem in the class of all graphs.     

Approximation of max independent set, min vertex cover and related problems by moderately exponential algorithms

Using ideas and results from polynomial time approximation and exact computation we design approximation algorithms for several NP-hard combinatorial problems achieving ratios that cannot be achieved in polynomial time (unless a very unlikely complexity conjecture is confirmed) with worst-case complexity much lower (though super-polynomial) than that of an exact computation. We study in particular two paradigmatic problems, max independent set and min vertex cover.