Characterizing sets of data structures by the connectivity relation

A formalism based on the directed graph connectivity relation is presented, in which a first-order predicate calculus notation is used with the purpose of defining sets of data structures and characterizing the structural operations on them. The formalism is designed so as to facilitate the proof that the intended operations on instances of a given set of data structures are correct, in the sense that they do not violate the structural form of the data.     

Computing with graphs and graph transformations

Many software applications require the construction and manipulation of graphs. In standard programming languages, this is accomplished using low‐level mechanisms such as pointer manipulation or array indexing. In contrast, graph productions are a convenient high‐level visual notation for coding graph modifications. A graph production replaces one subgraph by another subgraph. Graph productions can define a graph grammar and graph language, or can directly transform an input graph into an output graph. Graph transformation has been applied in many areas, including the definition of visual languages and their tools, the construction of software development environments, the definition of constraint programming algorithms, the modeling of distributed systems, and the construction of neural networks. One application is presented in detail: the interpretation of mathematical notation in scanned document images. The graph models the set of mathematical symbols, and their spatial and logical relationships. This graph is transformed by productions written in the PROGRES language. Copyright © 1999 John Wiley & Sons, Ltd.     

Minimal functional routes in directed graphs with dependent edges

Graphs are mathematical structures used to model a set of objects and the relations between them. One of the basic concepts of graph theory, the path, has wide real‐world applications. In classic graph models, edges ending at a node are assumed to be independent. However, many real graphs/networks can only be correctly described by considering a dependency among nodes or edges. Paths in such graphs may not be functional if the conditional dependency is ignored. In this study, we investigate the routing problem in directed graphs with dependent edges represented by general graph models as alternatives to hypergraphs. We define a minimal functional route (MFR) as a minimal set of nodes and edges that can independently perform information transfer between two given nodes, and formulate the determination of MFRs as a graph search problem. A depth‐first‐search (DFS) top‐down algorithm, an iterative integer linear programming (ILP) bottom‐up algorithm, and a subgraph‐growing bottom‐up algorithm are devised subsequently to solve this problem. Numerical experiments verify the effectiveness of the algorithms. The defined MFR problem and the proposed algorithms are expected to find many practical applications.     

Distributed consensus filter on directed switching graphs

We consider distributed estimation on a directed graph with switching topologies. Motivated by a recent PI consensus filter, we modify the protocol and remove the requirement of bidirectional exchange of neighboring gains for fixed topologies. We then extend the protocol to switching topologies and propose a new hybrid consensus filter design. Convergence results under both balanced directed, and general directed graphs are given for switching graphs. Consensus error bounds are analytically derived in the case of time‐varying inputs. Satisfactory simulation results are shown. Copyright © 2014 John Wiley & Sons, Ltd.     

Dynamic consensus estimation of weighted average on directed graphs

Recent applications call for distributed weighted average estimation over sensor networks, where sensor measurement accuracy or environmental conditions need to be taken into consideration in the final consensused group decision. In this paper, we propose new dynamic consensus filter design to distributed estimate weighted average of sensors’ inputs on directed graphs. Based on recent advances in the filed, we modify the existing proportional-integral consensus filter protocol to remove the requirement of bi-directional gain exchange between neighbouring sensors, so that the algorithm works for directed graphs where bi-directional communications are not possible. To compensate for the asymmetric structure of the system introduced by such a removal, sufficient gain conditions are obtained for the filter protocols to guarantee the convergence. It is rigorously proved that the proposed filter protocol converges to the weighted average of constant inputs asymptotically, and to the weighted average of time-varying inputs with a bounded error. Simulations verify the effectiveness of the proposed protocols.     

Transformations of fuzzy graphs specified by <Emphasis Type="Italic">FD</Emphasis>-grammars

The categorical approach is proposed to formalize transformations of FD-graphs that consist of networks of distributed components whose nodes are specified by fuzzy graphs. Necessary and sufficient conditions are formally defined for FD-graph transformations that do not violate structure integrity and can be constructed componentwise. FD-grammars that generalize fuzzy graph grammars are proposed to describe the admissible transformations of FD-graphs. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 129–147, March–April 2007.     

Multi-level association rules and directed graphs for spatial data analysis

We propose a methodology that upgrades the methods of the Lagrangian analysis of surface sea-water parcels. This methodology includes data mining with efficient visualization techniques, namely, spatial–temporal association rules and multi-level directed graphs with different levels of space and time granularity. In the resulting multi-level directed graphs we can intertwine knowledge from various disciplines related to oceanography (in our application) and perform the mining of such graphs. We evaluate the proposed methodology on Lagrangian tracking of virtual particles in the velocity field of the numerical model called the Mediterranean Ocean Forecasting Model (MFS). We describe an efficient algorithm based on label propagation clustering, which finds cycles and paths in multi-level directed graphs and reveals how the number and size of the cycles depend on the seasons. In addition, we offer three interesting results of the visualization and mining of such graphs, that is, the 12 months periodicity of the exchange of water masses among sea areas, the separation of Mediterranean Sea circulation in summer and winter situations, obtained with the hierarchical clustering of multi-level directed graphs, and finally, with visualization with multi-level directed graphs we confirm the reversal of sea circulation in the Ionian Sea over the last decades. The aforementioned results received a very favorable evaluation from oceanographic experts.     

Observer-based prescribed-time consensus control for heterogeneous multi-agent systems under directed graphs

This work studies the prescribed-time robust consensus tracking problem of heterogeneous multi-agent systems over directed graphs. Aiming at multi-agent systems with a static leader and only matched disturbances, a distributed observer-based consensus algorithm is developed, to ensure that the tracking errors converge to zero accurately in prescribed time. For the case of multi-agent systems with a dynamic leader and mismatched/matched disturbances, an adaptive strategy based on a distributed observer and a disturbance observer is designed by the dynamic damping reciprocal technology. Such strategy can avoid the numerical singularity, adapt to the situation that the upper bounds of the disturbances are unknown, and assure that the tracking errors converge to an adjustable neighborhood of zero within prescribed time. Finally, simulations are given to verify the effectiveness of the proposed control strategies.     

运用有向图进行中文分词研究

首先说明了分词在中文信息处理中的作用,然后介绍了分词系统中的关键技术。提出了一种基于有向图的中文分词算法,该算法首先构造中文分词有向图,然后计算中文分词有向图中所有可能的切分路径,最后利用了最少分词原则、汉字之间的互信息和词语的频率等信息给中文分词有向图中的每条切分路径打分,分数最高的路径就对应正确的切分结果。开放测试结果表明分词精确率可达90%以上。     

Toward a mathematical theory of graph-generative systems and its applications

This paper presents some formal generative specifications for describing the graph languages consisting of the sets of directed graphs with labeled arcs. Some mathematical results are introduced. In addition, we consider applications to specification technique for data structures and complexity measure of computer software. Finally, directions for future research are indicated.     

基于有向图的二进制文件结构化比较机制研究

通过对二进制文件结构化比较方法的研究,提出了基于有向图的二进制文件结构化比较方法及实现算法.和基于指令比较的二进制文件比较方法相比,二进制文件结构化比较方法更注重二进制文件在逻辑结构上的变化,而且更加简单.     

一种基于有向图的工作流测试方法

已有工作流测试方法在测试完备性和充分性方面存在不足。针对此问题文章对有向图工作流模型进行扩展,提出了一种新的工作流测试方法,设计并实现了其算法。该方法能够自动生成完备且充分的测试路径和测试用例。实例验证该方法有效。     

一种基于有向无环图的本体内聚度度量方法

目前,随着本体的广泛使用和快速发展,本体在结构与语义上变得越来越复杂。如何对本体的质量进行评估成为本体构建和重用的主要问题。在本体构建过程中,对本体进行评估有利于对本体进行重构和优化,以构建高质量的本体。在本体重用过程中,可以帮助用户在候选本体集中选择最优结构的本体。提出一种基于有向无环图(DAG)的本体内聚度度量方法,首先依据有向无环图的结构提出一组本体内聚度度量指标;然后根据已有的度量验证框架对其进行验证,说明度量指标在理论上有效;最后使用经典本体数据集进行实验,说明所提出的本体内聚度度量方法的合理性和有效性,有利于本体的构建和重用。     

Verification of conceptual schemata based on hybrid object-oriented and logic paradigm

Contemporary conceptual modelling languages are concerned with the representational adequacy of knowledge about a universe of discourse and with the efficient organization of this knowledge in structures that help overcome the problems of size and complexity in the modelled reality. In the paper it is argued that a conceptual modelling language should also facilitate the verification of captured requirements by exercising the conceptual schemata derived from the use of such a language. A conceptual modelling language is presented that is based on a hybrid representation scheme that makes use of object-oriented and logic approaches, and it is shown how this language can be used to verify requirements during the development of information systems.     

基于大数据时代的数据可视化应用分析

如今随着数据采集、存储和数据分析技术飞速发展,大幅度降低了数据储存和处理的成本,我们即将步入一个大数据时代。大数据时代的改革将海量数据处理变为可能,而且大幅降低了处理成本,促使越来越多跨专业学科的人才投入到大数据的开发应用中来。如何才能让大型数据集变得简单和易于理解,可视化无疑是最有效的途径。对大数据背景下的数据可视化应用展开研究,将有助于我们发展和创新数据可视化技术。     

基于有向图的数据流图的E-R模型构建方法

建立概念模型是数据库设计的重要步骤之一,E-R模型是数据库设计中广泛采用的概念模型。本文提出利用业务分析过程中形成的数据流图,把数据流图抽象为有向图,从而构建E-R模型的方法。在大型系统数据库设计过程中,使用这一方法可以快速构建局部应用的E-R模型,大大缩短数据库设计过程中构建E-R模型所耗费的时间。实例验证了本方法在实际工程项目中的实用性和有效性。     

基于十字链表的多刚体系统的数据存储

针对多刚体系统数据存储的不足,对多刚体系统的结构图与图论的有向图之间的关系进行了研究,提出了一种新的基于十字链表的链式存储模型.该存储模型不但较好地解决了复杂多刚体系统的存储问题,而且充分满足了在存储物理多刚体系统时的结构正确性和数据完备性要求,避免了非树形多刚体向树形多刚体的回路切除转换,使多刚体系统在数学建模与数据存储方面达到高度一致.     

基于图像数据挖掘的有向图模型检索方法

为充分挖掘图像数据信息,提出了一种有向图模型检索方法,结合距离测度初次检索和有向图距离二次检索提高图像检索性能。首先,采用传统的纹理、边缘和颜色特征以及特征之间的欧氏距离测度来进行初次检索,得到一个查询排序列表;在此基础上,结合距离测度与余弦测度设计图像之间的相关测度,在不同的相关测度阈值下构建图像数据集的有向图模型集合;最后,计算有向图距离,据此进行二次检索,降低误检现象。在COREL和ImageCLEF两个数据集上的图像检索实验结果表明,该方法的平均精确度和平均召回率指标高。     

基于多中间件的数据集成方案

为了实现分布的异构数据集成,解决"信息孤岛"问题,结合J2EE架构的优势和许多成功的数据集成方案,提出了基于数据访问中间件、消息中间件、数据源集成中间件的数据集成方案.详细讲述了该集成方案的架构和实现,实现结果表明该方案明显提高了数据集成的效率.最后,结合最新技术发展趋势对数据集成的研究前景做出了展望.