Abstract
〈Vol.6 No.2(2013.3)〉
Titles
[Contributed Papers]
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■ Maximizing Cascade of Innovation on Networks
National Defense Academy・Takanori KOMATSU, Hiroshi SATO, and Akira NAMATAME
Diffusion of innovation is usually difficult, because many members in society had not adopted innovation initially and people are usually rational: they select risk dominant solution and keep initial state. Cascade phenomena, which are sequences of adoption by agents, are the important driven forces for the society to make a successful diffusion of innovation, emergence of social norm and opinion formation. There are certain kinds of networks (ex. social network) under these cascade phenomena and the topologies will affect the dynamics. The cascade phenomena can occur in specified range of conditions (or known as cascade windows) defined by both the average degree of the underlying network topologies and the threshold of each agents (or nodes). This paper shows what kind of network topology maximizes cascade of innovation in terms of cascade window using evolutionary optimization method and how the network topology drives cascade phenomena at wider conditions than other networks. From results of the optimization, the best networks have both cluster of hub nodes and cluster of nodes with a few links, which are called vulnerable nodes. By a detailed consideration of topologies of the best networks, the authors also propose a network model (P model) to maximize the cascade of innovation, in which a mechanism of probabilistic growing network is used. At each discrete time step, one new node and constant number of new links are introduced and added to hub nodes or vulnerable nodes in the network depending on a certain probability. The P model has better scalability compared with evolutionary optimizing method in terms of time complexity and can make networks that drive cascade phenomena at wider conditions than evolutionary optimized networks. The success of P model strengthens the importance of both cluster of hub nodes and cluster of vulnerable nodes for maximizing cascade of innovation on networks.
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■ Informative and Normative Effects Using a Selective Advertisement
University of Tsukuba・Setsuya KURAHASHI and BrainPad Inc.・Muneyoshi SAITO
This paper discusses how the neighbours affect the decision of consumer
behaviour over diffusion of innovation. An agent-based model of diffusion
is proposed on an online social network which have both “scale-free”
and “regular” properties. The findings of the studies of consumer activity
in order to show the following points: 1) the informative effect can cause
a take-off, but it is not sufficient to reach the completion of diffusion,
2) the combination of the informative and normative effects can easily
bring a take-off, which is a point in time within the adoption curve that
the existence of a sufficient amount of adopters of an innovation or a
product. After the take-off, the diffusion is accelerated and reaches the
completion in the end, 3) the informative effect makes information propagate
fast, and so does the normative effect over a network that has characteristics
of scale-free and high cluster, 4) in a selective advertisement, the most
effective approach is non-selective advertisement for all consumers. This
paper shows that it is inadequate to think that opinion leaders only adopt
a product and transmit the information of usability impressions to other
consumers in order to trigger diffusion on online human-relationship networks.
Rather, diffusion is promoted entirely by active communication among non-opinion
leaders which have received such information from opinion leaders.
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■ Modeling of Information Sharing on the Business Social Media
The University of Tokyo・Fujio TORIUMI, NTT Information Sharing Platform
Laboratories・Takashi OKADA, Nagoya University,・Shuichiro YAMAMOTO, and
Kenichiro ISHII
Social media, which support communication on the Internet, continue to
spread rapidly. SNSs and micro-blogs are typical services. This research
proposes methods for efficient information sharing through social media,
especially intra-firm systems for information sharing of research or expertise.
In this research, a simple model of social media is provided, whose users
share information by directly referring to other users. The authors focused
on a particular intrafirm social media and analyzed the usage of its communities.
By applying a clustering method, they are classified into six groups and
analyzed their characteristics and occupation rate. Finally, the authors
proposed a method that supports information sharing and evaluated it by
agent-based simulation using our proposed model. The authors clarified
that not only encouraging users to post articles but also giving them an
opportunity to refer to the existing community’ s history is effective
for information sharing.
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■ Hierarchical-Game Based Multi-Attribute Negotiation of Supply Chain
Network
Kobe University・Fang YU, Toshiya KAIHARA, and Nobutada FUJII
This paper focuses on hierarchical-game based multi-attribute negotiation
between multiple MAs (Manufacture Agents) and multiple MSAs (Material Supplier
Agents) of SCN (Supply Chain Network). The attributes of the wholesale
price of the product, the quantity of the order and the lead time of the
order are negotiated simultaneously. A modified hierarchical-game based
negotiation protocol is proposed based on the previous work. It is a changeable
hierarchical game. It is a two-layer game when all the orders are in abilities
of all the MSAs. However, it is a three-layer game when there are some
orders out of abilities of some MSAs. The second layer game is not necessary,
it is triggered to find coalitions only if the order is out of ability
of MSA. The third layer game is used to determine the final quotation of
the negotiation. Then, the first layer game is aimed to find the optimal
allocation scheme to maximize the total profit of SCN based on the results
of the second and the third layer games. Numerical example is provided
to illustrate the proposed protocol.
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■ Ambiguity and Vagueness in Strategic Communication:An Evolutionary Approach
Future University Hakodate・Ryousuke NORI and Toshiji KAWAGOE
In this paper, the authors examine strategic communication including ambiguous
utterances. Recently, game theoretical approaches are introduced in the
study of pragmatics. Parikh’s paper is considered as one of the representative
studies. He shows that there exist equilibria including an ambiguous utterance
as a part of the equilibrium strategy in his model. However, his model
has some limitations. First of all, in his model, interests between the
sender and the receiver perfectly coincide, and secondly he analyzes with
a static solution concept. In this paper, Parikh’s model of ambiguous
utterances is extended by changing the degree of coincidence of interest
between the sender and the receiver, and is analyzed by evolutionary dynamics.
The authors found that ambiguous utterances can be a stable outcome with
certain conditions. Agent-based simulation also confirmed this finding.
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■ Evolutionary Leader Game and Social Hierarchy
University of Tsukuba,・Eizo AKIYAMA
This paper presents an evolutionary model of a population where individuals
play a repeated Leader Game where two agents each has two options to choose,
D (active/aggressive action: Daring, Dive) and C (passive action: Concede,
Careful). The simulation results show that the evolutionary process for
the Leader Game brings about a linear dominance hierarchy among strategy
(automaton) classes. The author also investigates the robustness of the
result against the perturbation of the game structure, the change of memory
size of automata and the introduction of behavioral error.
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■ Virtual Grounding for Facsimile Model Construction Where Real Data Is
not Available
Waseda University・Kotaro OHORI, Mariko IIDA, and Shingo TAKAHASHI
Recently, a need has arisen for facsimile model construction with close
correspondence to the real world for use in evaluating the effectiveness
of specific policies. When constructing facsimile models requiring a large
amount of data, however, parameter estimation using data fitting becomes
problematic. Furthermore, there are often problems where, owing to the
limitations of field research, it becomes impossible for analysts to obtain
the data necessary for model construction. The paper proposes a solution
to this data collection problem by using “virtual grounding” as a method
for creating valid agent models. The proposed method constructs an agent
model by isolating qualitative features of the real world situation that
are targets for modeling at a stage where the complete dataset is not yet
available, and uses standard models for which utility has been previously
demonstrated. Following this construction, a number of sample participants
modeled as agents repeatedly make hypothetical decision-making actions
within the model environment, and the model parameters are estimated based
on the results of these decisions. This paper demonstrates the utility
of the virtual grounding method by using an example of modeling visitor
agents to Tokyo Disney Sea.
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■ Specifying Collective Adaptive Situations in Cross Cultural Game towards
Validation of Agent-Based Social Simulation
The University of Electro-Communications・Keiki TAKADAMA and
NTT Data Corporation・Yuya USHIDA
This paper focuses on a collective adaptive situation as an complex phenomena
in social dynamics and aims at specifying its situation towards a validation
of agent-based social simulations. For this purpose, the fuzzy c-means
clustering (FCM) method is applied into the experimental data of both the
human subject experiments and the agentbased social simulations in the
cross-cultural game, Barnga, and compare these results from the viewpoint
of a collective adaptive situation. The analysis of these data has revealed
the following implications: (1) the collective adaptive situation can be
specified by the FCM method; and (2) the classified results of both of
the experimental data are close to each other, indicating that agent-based
social simulations can be validated from the viewpoint of a collective
adaptive situation.
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■ Making a Practical Policy Proposal for Polling Place Assignment Using Voting Simulation Tool
Kansai University・Tadahiko MURATA and Kenta KONISHI
Although a lot of researchers have interests to social simulations recently,
many of their outcomes can show just abstract lessons over simple settings
in their social simulations. It is understandable because complicate settings
will make their social simulation tool difficult to understand and tune
its parameters. There is a dilemma between simple settings with abstract
lessons and difficult settings with difficult tool tuning. In this paper,
it is shown that how social simulation tools can be used to make a policy
proposal for polling place assignment. In the previous study of authors,
a model was proposed for a decision making for each voter in an election.
The change of the polling places was considered in a city, Takatsuki, Osaka
Prefecture, Japan, to increase the voter turnout and to reduce the number
of polling places. A method was also proposed to identify regional polling
parameters in an election using real voter turnout records. With those
regional polling parameters, selection and assignment of polling places
to each region was done using an Evolutionary Multiobjective Optimization
(EMO) algorith. Several sets of solutions were found that increase the
voter turnouts and reduce the number of the polling places. In this paper,
the authors show several practical results after consulting the office
of the board of elections in the target city. In order to utilize outcomes
of social simulations practically, they are advised that they should show
the difference between the current voting assignment and the proposed one
in order to announce those who should vote in a different station. They
are also advised to show how to support those who should go to farther
polling stations after the change of polling stations. To meet these requests
from the office, they simulate a case with free shuttle bus service using
our model.
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■ A Development of Transportation Simulator for Relief Supply in Disasters
National Maritime Research Institute・Takahiro MAJIMA,
Tokyo University of Marine Science and Technology・Daisuke WATANABE,
The University of Electro-Communications・KeikiTAKADAMA,
and SocioTechData・Mitujiro KATUHARA
The Great East Japan Earthquake on March 11th, 2011 struck eastern coastal
area of the Japanese main island and tsunami following the earthquake posed
a devastated condition. Most infrastructures and lifelines, such as water
supply systems, petroleum gas supply systems and electric power systems
including Fukushima nuclear plant were damaged. Logistics systems are no
exception. The authors developed “Support System for Transportation under
Disaster Circumstance” comprised of three tools. This paper focusses on
one of the tools, transportation simulator for relief goods and demonstrated
functions of the simulator and simulation examples.
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■ Implementation of Simulation Environment for Exhaustive Analysis of Huge-Scale Pedestrian Flow
National Institute of Advanced Industrial Science and Technology (AIST)・Japan
Science and Technology Agency (JST)・Tomohisa YAMASHITA, Takashi OKADA,
and National Institute of Advanced Industrial Science and Technology (AIST)・Itsuki
NODA
This paper describes implementation of a pedestrian simulation environment
to carry out an exhaustive analysis of huge-scale pedestrian flow. Our
environment consists of the CrowdWalk pedestrian simulator and the PRACTIS
simulation controller. CrowdWalk has three pedestrian movement models that
are based on a one-dimensional space model. PRACTIS carries out an exhaustive
and efficient analysis in a cluster environment to support effective decisionmaking,
enabling pedestrians to be guided according to various criteria. The authors
apply CrowdWalk and PRACTIS in a firework festival to verify their guidance
planning, and examine some case studies.
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■ Relations between Partial Diversity and Organizational Performance in an Organization
This paper presents an agent-based simulation model to analyze performance
of organization with heterogeneous members. A hierarchical landscapes model
with organizational and personal landscapes is proposed and it puts difference
of skills and values into difference of personal landscapes. The use of
this model shows that an organization needs to have a certain amount of
diverse members to improve the whole organizational utility under the changing
environment. This is because while the uniform members stay at a state
with higher individual utility even if there are diverse members in the
organization, the diverse members discover a new state with higher organizational
utility and then take others to that state.
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Collaborative Task Casting: A Task Selection Technique for Multi-Task Autonomous Robots
The University of Tokyo・Kentaro ISHII and Keio University・Michita IMAI
As robot technology improves, autonomous robots expect to work in place
of humans. It is cost efficient when such autonomous robots are supposed
to perform multiple tasks. This paper deals with such multi-task robots
and proposes a task selection technique for multi-task autonomous robots.
When an autonomous robot is implemented for multiple purposes, it is important
that the robot be able to appropriately select its own tasks. The proposed
method, named collaborative task casting, takes degrees of task achievement
into account and balances task occupation to ensure that adequate robot
resources are directed towards each task. The experimental simulation results
showed that the proposed method had advantage over existing methods in
terms of minimizing unsatisfactory state and adaptively worked in many
possible settings.
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