Federated databases and systems: Part II — A tutorial on their resource consolidation

The issues and solutions for the interoperability of a class of heterogeneous databases and their database, systems are expounded in two parts. Part I presented the data-sharing issues in federated databases and systems (Hsiao, 1992). The present article explores resource-consolidation issues.Interoperability in this context refers to data sharing among heterogeneous databases, and to resource consolidation of computer hardware, system software, and support personnel.Resource consolidation requires the presence of a database system architecture which supports the heterogeneous system software, thereby eliminating the need for various computer hardware and support personnel. The class of heterogeneous databases and database systems expounded herein is termedfederated, meaning that they are joined in order to meet certain organizational requirements and because they require their respective application specificities, integrity constraints, and security requirements to be upheld. Federated databases and systems are new. While there are no technological solutions, there has been considerable research towards their development. This tutorial is aimed at exposing the need for such solutions. A taxonomy is introduced in our, review of existing research undertakings and exploratory developments. With this taxonomy, we contrast and compare various approaches to federating databases and systems.Editorial note: Portions of the introductory sections of Part II of this artlcle replicate material in Part I (Hsiao, 1992) in order to provide the reader with a self-standing article.     

ls-Ponomarev-systems与1-序列覆盖映像

为了寻求局部可分度量空间的映像,引入双点星sn覆盖这一概念,并借用近年来由传统的Ponomarev-system推广而得的ls-Ponomarev-system,给出了局部可分度量空间1-序列覆盖映像的一个新刻画,并且这一新刻画较以往所得相关刻画更为简洁.     

关于可数到一伪开映射

本文对可数到一伪开映射进行了讨论,得到了如下结果:(1)可数到一伪开映射保持CA_1-空间(CA_2-空间),(2)设T是一拓扑性质,且度量空间具有性质T,如果存在一个不具有性质T的满足(*)的Frechet空间,则可数到一伪开映射不保持性质T.(3)设拓扑性质T满足:(i)关于不相交的拓扑和保持,(ii)在可数到一伪开映射下保持,则性质T满足点可数半开和定理.     

关于Fuzzy映象的重合度理论

本文的目的是在工作[1]的基础上,进一步讨论Fuzzy映象和集值映象的重合度,本文的结果是引文[1]中相应结果的改进和推广.     

非凸集上映射的不动点及迭代逼近问题

讨论了非凸集上自映射的不动点存在问题,推广了文献〔1,2〕中的结论,其次考虑了用Picard迭代列逼近映射的不动点的问题,证明了一个迭代收敛定理。     

无向图中连通支配集问题的精确算法

图◢G=（V,E）的一个支配集DV是一个顶点子集,使得图中每一个顶点要么在D中,要么至少与D中的一个顶点相连。连通支配集问题是找到一个顶点数最小的支配集S,并且S的导出子图G［S］是连通图。◣该问题是一个经典的NP难问题,可应用于连通设施选址、自适应网络等领域。针对无向图中连通支配集问题,仔细分析该问题的图结构性质,挖掘出若干有效的约简规则和分支规则,设计了一个分支搜索算法,并采用了测量治之方法分析算法的运行时间,最终得到了一个运行时间复杂◢度为O*△（1.93n△）的精确◣算法。     

求解区间图上的罗马控制数的动态规划算法

摘 要: 针对区间图的最小罗马控制函数和罗马控制数求解的困难性,本文提出了一个动态规划算法。从区间图的顶点排序开始,结合区间图的某些性质,采用逐步搜索的方法,不断扩大搜索的顶点集合范围,最终求出最优的罗马控制集和罗马控制数。为保证算法的正确性和科学性,对算法进行了严格的数学推理和证明。最后还给出了一个典型的区间图求解过程的演示示例,增强了算法的可读性和可操作性。结果表明该算法不仅运算速度快,而且简单易行。 关键词: 区间图;罗马控制函数;罗马控制数;权重;动态规划算法     

On solving the minimization problem and the fixed-point problem for a finite family of non-expansive mappings in CAT(0) spaces

In this paper, we propose a new modified proximal point algorithm for a finite family of non-expansive mappings in the framework of CAT(0) spaces. We establish Δ-convergence and strong convergence theorems under some mild conditions. Our results extend some known results which appeared in the literature.     

Inducing strong convergence into the asymptotic behaviour of proximal splitting algorithms in Hilbert spaces

Proximal splitting algorithms for monotone inclusions (and convex optimization problems) in Hilbert spaces share the common feature to guarantee for the generated sequences in general weak convergence to a solution. In order to achieve strong convergence, one usually needs to impose more restrictive properties for the involved operators, like strong monotonicity (respectively, strong convexity for optimization problems). In this paper, we propose a modified Krasnosel'ski?–Mann algorithm in connection with the determination of a fixed point of a nonexpansive mapping and show strong convergence of the iteratively generated sequence to the minimal norm solution of the problem. Relying on this, we derive a forward–backward and a Douglas–Rachford algorithm, both endowed with Tikhonov regularization terms, which generate iterates that strongly converge to the minimal norm solution of the set of zeros of the sum of two maximally monotone operators. Furthermore, we formulate strong convergent primal–dual algorithms of forward–backward and Douglas–Rachford-type for highly structured monotone inclusion problems involving parallel-sums and compositions with linear operators. The resulting iterative schemes are particularized to the solving of convex minimization problems. The theoretical results are illustrated by numerical experiments on the split feasibility problem in infinite dimensional spaces.