Showing papers on "Network theory published in 1999"

The centrality of groups and classes

Abstract: This paper extends the standard network centrality measures of degree, closeness and betweenness to apply to groups and classes as well as individuals. The group centrality measures will enable researchers to answer such questions as ‘how central is the engineering department in the informal influence network of this company?’ or ‘among middle managers in a given organization, which are more central, the men or the women?’ With these measures we can also solve the inverse problem: given the network of ties among organization members, how can we form a team that is maximally central? The measures are illustrated using two classic network data sets. We also formalize a measure of group centrality efficiency, which indicates the extent to which a group's centrality is principally due to a small subset of its members.

Queueing networks- customers, signals, and product form solutions

Abstract: considerations. Most of these open problems are easily stated and put into a theoretical framework, but they often require either intricate techniques on an ad hoc basis or deep mathematical methods. Often, both of these approaches have to be combined to tackle successfully the solution of quickly formulated problem. The development of queueing network theory, which provided application areas with solutions, formulas, and algorithms, commenced around 1950 in the area of Operations Research, with special emphasis on production, inventory, and transportation. The first breakthroughs were the works of Jackson [10] and Gordon and Newell [10]; both papers appeared in Operations Research. The second breakthrough in queueing network theory was already connected with Computer Science: the celebrated papers of Baskett, Chandy, Muntz, and Palacios [2], which appeared in the Journal of the Association for Computing Machinery, and of Kelly [11]. The two volumes of Kleinrock’s book [13, 14] appeared at the same time as [11]. From that time on, queueing network theory and its applications have become intimately connected with performance analysis of complex systems in Computer and Communication Sciences, both at the hardware and software levels. Today’s growth of production, manufacturing, and transportation, with information processing and communi

Network Algebra

Abstract: From the Publisher: Network Algebra considers the algebraic study of networks and their behaviour. It contains general results on the algebraic theory of networks, recent results on the algebraic theory of models for parallel programs, as well as results on the algebraic theory of classical control structures. The results are presented in a unified framework of the calculus of flownomials, leading to a sound understanding of the algebraic fundamentals of the network theory." "The term 'network' is used in a broad sense within this book, as consisting of a collection of interconnecting cells, and two radically different specific interpretations of this notion of networks are studied. One interpretation is additive, when only one cell is active at a given time - this covers the classical models of control specified by finite automata or flowchart schemes. The second interpretation is multiplicative, where each cell is always active, covering models for parallel computation such as Petri nets or dataflow networks. More advanced settings, mixing the two interpretations are included as well." "Network Algebra will be of interest to anyone interested in network theory or its applications and provides them with the results needed to put their work on a firm basis. Graduate students will also find the material within this book useful for their studies.

A New Model for Information Diffusion in Heterogeneous Social Networks

Abstract: This paper discusses a new model for the diffusion of information through heterogeneous social networks. In earlier models, when information was given by one actor to another the transmitter did not retain the information. The new model is an improvement on earlier ones because it allows a transmitter of information to retain that information after telling it to somebody else. Consequently, the new model allows more actors to have information during the information diffusion process. The model provides predictions of diffusion times in a given network at the global, dyadic, and individual levels. This leads to straightforward generalizations of network measures, such as closeness centrality and betweenness centrality, for research problems that focus on the efficiency of information transfer in a network. We analyze in detail how information diffusion times and centrality measures depend on a series of network measures, such as degrees and bridges. One important finding is that predictions about the time ...

An interaction-cost perspective on networks and territoryInteraction-cost perspective on networks

Abstract: This paper aims to contribute to the development of a general network theory for the social sciences. This ambition comprises an attempt to a) formulate, and illustrate with historical examples, a general hypothesis about the relation between a contiguity and a network principle for spatial development, and to b) use the concept of interaction costs to illuminate the genesis and shaping of networks, the interaction between and within them, and implications of the fact that networks have different durability and potential for change. An attempt is made to break interaction cost-generating factors down into groups according to their potential for change. The concept of affinity is viewed as a part of the aggregate relationship between homogeneity and heterogeneity in the nodes of the respective networks – a relationship which constitutes one component of the totality of factors underlying interaction costs. The paper points out certain theoretical research issues such as the relationship between networks and politically-controlled territories; links between various external networks; links and flows within complex nodes; relationships between internal, „intra-nodal” and external networks and the processes in which a one-function node bifurcates from one network to another; the generation of links for various flows by nodes but also the impact made by the flows on the internal structure of complex nodes. A more systematic application of network theory to these (and other) fields seems to have the potential of producing important contributions to the understanding of economic development.

Centrality in Policy Network Drawings

Abstract: We report on first results of a cooperation aiming at the usage of graph drawing techniques to convey domain-specific information contained in policy or, more general, social networks. Policy network analysis is an approach to study policy making processes, structures and outcomes, thereby concentrating on the analysis of relations between policy actors. An important operational concept for the analysis of policy networks is centrality, i.e. the distinction of actors according to their importance in a relational structure. Matching structural with geometric centrality we incorporate the aggregated values of centrality measures into a layout model of the network.

Graph theoretic or computational geometric research of cellular mobile communications

Abstract: The demand fur communication services is rapidly increasing, because the mobile communication service is synonymous of an ideal communication style realizing communication in any time, any where and with anyone There exist various problems to which computational geometry and graph and network theory is applicable in mobile communication services For example, it is well known that coloring algorithms of graphs are applicable in channel assignment algorithms in cellular systems In this paper, we show new results in graph theoretic or computational geometric research of cellular mobile communications

On a minimax realization problem on flow networks

Abstract: We consider a realization problem of an undirected flow network N from a matrix M We assume that M is not always a terminal capacity matrix In our previous study, we considered a problem to minimize the differences between capacities between vertex pairs in N, and elements of M We called this problem "minimax realization problem" In this paper, we propose another minimax realization problem and propose an algorithm to minimize the differences