FORBIDDEN SUBGRAPHS,DEGREES,NEIGHBORHOOD UNIONS AND CIRCUMFERENCES OF GRAPHS

Combining forbidden subgraphs with degree restrictions and neighborhood unionrestrictions,respectively,we prove the following results:(1) Let G be a 2-connected graph of order n,and 3≤c≤n.If for each induced subgraphL of order four of G(?)|V_1(L)∩S_c|≥2 if L≌K_(1,3),and |V(L)∩S_c|≥1 if L≌P_4,then thecircumference of G is at least c,where V_1(L)is the set of vertices with degree 1 of L,S_c isthe set of vertices with degree at least c/2 of G and P_4 is a path of order 4.(2) Let G be a 2-connected graph of order n,and n≥s+2.If for each induced subgraphL of G isomorphic to K_(1,3)or P_4,d_L(u,v)=2(?)|N(u)∪N(v)|≥s,then the circumferencec (G) of G is at least s+2.Moreover,if n≥s+3 and s is odd,then c(G)≥s+3.     

城市"社区"是否可能?--关于农村邻里空间与城市邻里空间的比较分析

一种观点认为,当代中国城市邻里可以培育出经典意义上的社区共同体。通过理论与经验两方面的分析表明,城市中很难出现经典意义上的社区共同体。在城市邻里与农村邻里比较分析的基础上,提出了有关城市社区之所以不“可能”的一项解释。     

内积空间的算子是保内积算子的等价条件

本文主要给出在没有线性算子前提下一个算子是保内积算子的若干个等价命题     

无冗余第三范式及其规范算法

本文提出无冗余第三范式,并给出它的规范算法,消除了第三范式(3NF)中冗余的属性,而且本文的算法产生的关系模式数很少.     

信贷决策机制中的担保人的经济意义分析

讨论在不完全信息下完全竞争的信贷市场中，当借款方不能提供银行方所需抵押品时，借款方引入担保人后的经济意义．给出了在对风险的均值保持展形［５～７］的刻画下，借款方引入担保人后，银行的信贷决策机制．揭示了在此机制作用下，银行方可以消除信贷配给并给出了在此机制作用下，包含担保人的信贷决策机制优于不包含担保人的信贷决策机制的条件     

L-fuzzy拓扑空间中的N-导算子

引入并系统地讨论了L-fuzzy拓扑空间的N-聚点与N-导算子,结果表明它们具有一般拓扑学中相应的几乎全部结论。例如杨忠道定理成立;X_λ为L-fuzzy集A的N-聚点当且仅当A-x_1中有收敛于x_λ的分子网;(A∨B)~(d*)=A~(d*)∨B~(d*)等等。     

ON PROPERTIES OF THE PROPER SUBCLASS OF A UNIVALENT FUNCTION

This paper discusses the function class Hβ(a) of the from f(z)=z ∑k=(n 1)^ ∞, which satisfies the conditon Re[f‘(Z) βzf″(z)]＞a, (0≤a＜1) in |z|＜1, with its inclusion relation ,neighborhood properties and the deviation theorem ,convolution properties in the case when f(z) has negative coefficients.     

AN EMBEDDING OPERATOR FOR FUZZY NUMBER SPACE E~1 AND ITS APPLICATION FOR FUZZY INTEGRAL

In this paper,we give an order-preserving,isometric and isomorphic embeddingoperator from the fuzzy number space E~1 to a classical Banach space and show some necessary andsufficient integrability conditions of fuzzy integrals which were defined by M.Matloka and O.Kaleva by means of such an operator.