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Volume 24 (2007)
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- Issue 3 Pages 3_111-
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Volume 24, Issue 1
Displaying 1-10 of 10 articles from this issue
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Satoshi KURIHARA2007 Volume 24 Issue 1 Pages 1_1-1_2
Published: 2007
Released on J-STAGE: June 11, 2007
JOURNAL FREE ACCESSDownload PDF (31K) -
Shin-ya SATO2007 Volume 24 Issue 1 Pages 1_3-1_11
Published: 2007
Released on J-STAGE: June 11, 2007
JOURNAL FREE ACCESSSystems being made up of interrelated elements, such as social organizations and the Internet, can be regarded as networks, where nodes and links respectively correspond to the elements and the relationships among the elements. This perspective enables us to grasp the nature of systems in terms of structural characteristics of corresponding networks. For example, we can locate important elements in systems, and furthermore, compare and classify systems based on styles in which they are built, by structural analysis and modeling of their networks. The viewpoint that tries to uniformly understand various systems, even from different disciplines such as systems in nature and artificial systems, in terms of network structure helps us discovering universal characteristics of behavior and development of the systems. To show the aim, significance and potential of this approach, this paper discusses and introduces important works on the following three topics; structural analysis of networks, models of networks, and their practical applications.View full abstractDownload PDF (153K) -
Yoshiaki SONODA2007 Volume 24 Issue 1 Pages 1_12-1_23
Published: 2007
Released on J-STAGE: June 11, 2007
JOURNAL FREE ACCESSManufacturing industries have been recently forced to survive the low-cost competition in the globalization of the market with respect to product development, and to seek a new way to “transform” themselves to adopt the light speed markets, which have never been experienced. One reason is the emergence of the defects of organizational structure as a result of exponential and quantitative progress in IT. For the continuing existence of the organizations in the Information Age, the new systematic approach for the transformation is necessary, recognizing the natures and leveraging them in a positive manner, which existed genuinely in the variety of network structures behind them. This paper focuses on “Network Centric Strategy” which has gotten a lot of attention recently and show its practical aspect as organization strategy with respect to deep relationship with the complex network theory.View full abstractDownload PDF (1240K) -
Takashi ISHIKAWA, Satoshi KURIHARA2007 Volume 24 Issue 1 Pages 1_24-1_39
Published: 2007
Released on J-STAGE: June 11, 2007
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Yusuke MATSUMURA, Hidenori KAWAMURA, Azuma OHUCHI2007 Volume 24 Issue 1 Pages 1_40-1_49
Published: 2007
Released on J-STAGE: June 11, 2007
JOURNAL FREE ACCESSWhen composing networks for a particular purpose, we previously designed optimal topology for that purpose. Many researches so far have focused on designing optimal topology under various conditions given statically. However, in more than a few cases, the network is used during its growing process because it is difficult to construct a whole network at a burst when considering the construction of an actual network. In this paper, we investigate the feasibility of building an optimal network from the aspects of the optimality and growth elements of topologies. We lead the optimal growing rules for some conditions and take up network models mentioned in the research of complex networks. Experimental results verify that optimal growing rules vary depending on the purposes and conditions of the building of networks and show that the selection of the growing rules makes it possible to build networks optimally.View full abstractDownload PDF (190K) -
Kohsuke YANAI, Hitoshi IBA2007 Volume 24 Issue 1 Pages 1_50-1_61
Published: 2007
Released on J-STAGE: June 11, 2007
JOURNAL FREE ACCESSWe propose a novel model for scale-free networks that uses a rank-based selection. The proposed model produces networks according to the rank assigned to each node. It selects a certain number of nodes randomly and makes two evenly-divided groups of selected nodes. It then adds a new link between the two nodes which have the highest rank in each group. By repeating these steps, scale-free networks are generated. In this paper, we show that networks obtained from our model have a scale-free property through a theoretical proof and simulation results. These results indicate that the exponent of the degree distribution is roughly equivalent to 1. We also discuss the difference from the previous models and its applications to real-world networks.View full abstractDownload PDF (221K) -
Hiroshi KURAOKA, Nobutada FUJII, Kanji UEDA2007 Volume 24 Issue 1 Pages 1_62-1_69
Published: 2007
Released on J-STAGE: June 11, 2007
JOURNAL FREE ACCESSNumerous studies have examined how cooperation emerges in complex networks. It is necessary to take into account simultaneously the emergent characteristics of the network structure itself through interactions among agents and the emergent network dynamics: these points are inseparable in the real world. Furthermore, it is important to consider the information distribution among the elements because elements in the real world have structural restrictions and act under incomplete information. This paper introduces information distribution to a spatial prisoner's dilemma. We examine the emergence of cooperation through interactions among agents. Results show that a robust form of cooperation emerges when information distribution is considered.View full abstractDownload PDF (257K) -
Yoshifumi ISHIDA, Hitoshi YAMAMOTO, Isamu OKADA, Toshizumi OHTA2007 Volume 24 Issue 1 Pages 1_70-1_80
Published: 2007
Released on J-STAGE: June 11, 2007
JOURNAL FREE ACCESSIs cooperation evolutionally stable in the iterated prisoner's dilemma (IPD) game in which individuals interact on a scale-free network? Or what is an appropriate strategy for keeping cooperation stably in the game? We simulate a scale-free network of interactions among individuals in the IPD game and use an agent-based approach to investigate dynamics of the emergence of cooperation and the cooperation collapses. Our results are the following: 1) On the scale-free network, we can achieve cooperation to be sustainable, but it is vulnerable to collapse. 2) The reason cooperation collapses is that agents who have high node degrees are tolerant of others. A high level of cooperation is sustainable when those agents are strict to others. 3) What agents with high node degrees act non-cooperatively with a slight probability has effects to inhibit tolerance among individuals and to prevent invasion of defections.View full abstractDownload PDF (287K) -
Kazuhiro KAZAMA, Shin-ya SATO, Kazumi SAITO, Takeshi YAMADA2007 Volume 24 Issue 1 Pages 1_81-1_90
Published: 2007
Released on J-STAGE: June 11, 2007
JOURNAL FREE ACCESSWe present a SR-2 method to extract overlapping community structures from a human relationship network. It is a method of spectral graph analysis and is a variation of a SR method, which can extract a set of densely connected nodes from a network, changed for the more detailed extraction of co-occurrence networks. To investigate the characteristics of a SR method, a SR-2 method, and a k-community method, we visualized the results of extraction by their methods and evaluated the performance of extraction on a small human relationship network extracted from Web space. And we analyzed the distribution of node set sizes on a large co-authorship network. These results show that a SR-2 method can extract adequate community structures corresponding to real human communities.View full abstractDownload PDF (327K) -
Yoshiko HANADA, Fumitaka SATO, Tomoyuki HIROYASU, Mitsunori MIKI, Yasu ...2007 Volume 24 Issue 1 Pages 1_91-1_100
Published: 2007
Released on J-STAGE: June 11, 2007
JOURNAL FREE ACCESSIn this study, designing networks is formulated as an optimization problem with objective functions regarding characteristics of networks. We introduce an approach to find the contributing factors to construct complex networks by comparing and examining the characteristics between generated networks and the complex network. In this paper, we apply a genetic algorithm (GA) as optimization method and examine the network design focusing on characteristics of the complex network as basic studies for our proposal approach. Here the average shortest movement distance and/or the cluster coefficient are used as objective functions to construct networks. Through the experiments, it was clear that there was trade-off between these two factors and the multi-objective design was more appropriate than single-objective one, for applying our approach to real networks.View full abstractDownload PDF (726K)
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