The paper studies distributed static parameter (vector) estimation in sensor
networks with nonlinear observation models and noisy inter-sensor
communication. It introduces \emph{separably estimable} observation models that
generalize the observability condition in linear centralized estimation to
nonlinear distributed estimation. It studies two distributed estimation
algorithms in separably estimable models, the $\mathcal{NU}$ (with its linear
counterpart $\mathcal{LU}$) and the $\mathcal{NLU}$.
Adaptive networks are well-suited to perform decentralized information
processing and optimization tasks and to model various types of self organized
and complex behavior encountered in nature. Adaptive networks consist of a
collection of agents with processing and learning abilities. The agents are
linked together through a connection topology, and they cooperate with each
other through local interactions to solve distributed inference problems in
real-time.
This very short article aims to bring together the available bibliography on
multi-level (or multi-layer, multi-perspective, multi-view, multi-scale,
multi-resolution) agent-based modeling so that it is accessible to interested
researchers.
Understanding how spatial configurations of economic activity emerge is
important when formulating spatial planning and economic policy. A simple model
was proposed by Simon, who assumed that firms grow at a rate proportional to
their size, and that new divisions of firms with certain probabilities relocate
to other firms or to new centres of economic activity. Simon's model produces
realistic results in the sense that the sizes of economic centres follow a Zipf
distribution, which is also observed in reality.
One of the strength of Virtual Organisations is their ability to dynamically
and rapidly adapt in response to changing environmental conditions. Dynamic
adaptability has been studied in other system areas as well and system
management through policies has crystallized itself as a very prominent
solution in system and network administration. However, these areas are often
concerned with very low-level technical aspects.
The concept of dynamic coalitions (also virtual organizations) describes the
temporary interconnection of autonomous agents, who share information or
resources in order to achieve a common goal. Through modern technologies these
coalitions may form across company, organization and system borders. Therefor
questions of access control and security are of vital significance for the
architectures supporting these coalitions.
During the execution of large scale construction projects performed by
Virtual Organizations (VO), relatively complex technical models have to be
exchanged between the VO members. For linking the trade and transfer of these
models, a so-called multi-model container format was developed. Considering the
different skills and tasks of the involved partners, it is not necessary for
them to know all the models in every technical detailing. Furthermore, the
model size can lead to a delay in communication.
This volume contains the proceedings of the 3rd International Workshop on
Formal Aspects of Virtual Organisations (FAVO 2011). The workshop was held in
Sao Paulo, Brazil on October 18th, 2011 as a satellite event to the 12th IFIP
Working Conference on Virtual Enterprises (PRO-VE'11). The FAVO workshop aims
to provide a forum for researchers interested in the application of formal
techniques in the design and analysis of Virtual Organisations.
This work deals with coupling Clinical Decision Support System (CDSS) with
Computerized Prescriber Order Entry (CPOE) and their dynamic plugging in the
medical Workflow Management System (WfMS). First, in this paper we argue some
existing CDSS representative of the state of the art in order to emphasize
their inability to deal with coupling with CPOE and medical WfMS.
We consider the problem of information fusion from multiple sensors of
different types with the objective of improving the confidence of inference
tasks, such as object classification, performed from the data collected by the
sensors.
A Multi-Agent System is a distributed system where the agents or nodes
perform complex functions that cannot be written down in analytic form.
Multi-Agent Systems are highly connected, and the information they contain is
mostly stored in the connections. When agents update their state, they take
into account the state of the other agents, and they have access to those
states via the connections. There is also external, user-generated input into
the Multi-Agent System. As so much information is stored in the connections,
agents are often memory-less.
We provide a brief description of the Python-DTU system, including the
overall design, the tools and the algorithms that we plan to use in the agent
contest.
A multiagent system may be thought of as an artificial society of autonomous
software agents and we can apply concepts borrowed from welfare economics and
social choice theory to assess the social welfare of such an agent society. In
this paper, we study an abstract negotiation framework where agents can agree
on multilateral deals to exchange bundles of indivisible resources. We then
analyse how these deals affect social welfare for different instances of the
basic framework and different interpretations of the concept of social welfare
itself.
Effective coordination of agents actions in partially-observable domains is a
major challenge of multi-agent systems research. To address this, many
researchers have developed techniques that allow the agents to make decisions
based on estimates of the states and actions of other agents that are typically
learnt using some form of machine learning algorithm. Nevertheless, many of
these approaches fail to provide an actual means by which the necessary
information is made available so that the estimates can be learnt.
Many current large-scale multiagent team implementations can be characterized
as following the belief-desire-intention (BDI) paradigm, with explicit
representation of team plans. Despite their promise, current BDI team
approaches lack tools for quantitative performance analysis under uncertainty.
Distributed partially observable Markov decision problems (POMDPs) are well
suited for such analysis, but the complexity of finding optimal policies in
such models is highly intractable.
We examine properties of a model of resource allocation in which several
agents exchange resources in order to optimise their individual holdings. The
schemes discussed relate to well-known negotiation protocols proposed in
earlier work and we consider a number of alternative notions of rationality
covering both quantitative measures, e.g. cooperative and individual
rationality and more qualitative forms, e.g. Pigou-Dalton transfers.
This study presents a georeferenced agent-based model to analyze the climate
change impacts on the ski industry in Andorra and the effect of snowmaking as
future adaptation strategy. The present study is the first attempt to analyze
the ski industry in the Pyrenees region and will contribute to a better
understanding of the vulnerability of Andorran ski resorts and the suitability
of snowmaking as potential adaptation strategy to climate change.
The way of analyzing, designing and building of real-time projects has been
changed due to the rapid growth of internet, mobile technologies and
intelligent applications. Most of these applications are intelligent, tiny and
distributed components called as agent. Agent works like it takes the input
from numerous real-time sources and gives back the real-time response. In this
paper how these agents can be implemented in vehicle traffic management
especially in large cities and identifying various challenges when there is a
rapid growth of population and vehicles.
Multiagent learning is a necessary yet challenging problem as multiagent
systems become more prevalent and environments become more dynamic. Much of the
groundbreaking work in this area draws on notable results from game theory, in
particular, the concept of Nash equilibria. Learners that directly learn an
equilibrium obviously rely on their existence. Learners that instead seek to
play optimally with respect to the other players also depend upon equilibria
since equilibria are fixed points for learning. From another perspective,
agents with limitations are real and common.
There is an increasing need for automated support for humans monitoring the
activity of distributed teams of cooperating agents, both human and machine. We
characterize the domain-independent challenges posed by this problem, and
describe how properties of domains influence the challenges and their
solutions. We will concentrate on dynamic, data-rich domains where humans are
ultimately responsible for team behavior. Thus, the automated aid should
interactively support effective and timely decision making by the human.
Social dynamics determined by voting in a stochastic environment is analyzed
for a society composed of two cohesive groups of similar size. Within the model
of random walks determined by voting, explicit formulas are derived for the
capital increments of the groups against the parameters of the environment and
"claim thresholds" of the groups. The "unanimous acceptance" and "unanimous
rejection" group rules are considered as the voting procedures. Claim
thresholds are evaluated that are most beneficial to the participants of the
groups and to the society as a whole.
We consider the decentralized binary hypothesis testing problem on trees of
bounded degree and increasing depth. For a regular tree of depth t and
branching factor k>=2, we assume that the leaves have access to independent and
identically distributed noisy observations of the 'state of the world' s.
Starting with the leaves, each node makes a decision in a finite alphabet M,
that it sends to its parent in the tree. Finally, the root decides between the
two possible states of the world based on the information it receives.
To a large degree information and services for chemical e-Science have become
accessible - anytime, anywhere - but not necessarily useful. The Rule Responder
eScience middleware is about providing information consumers with rule-based
agents to transform existing information into relevant information of practical
consequences, hence providing control to the end-users to express in a
declarative rule-based way how to turn existing information into personally
relevant information and how to react or make automated decisions on top of it.
The paper studies the visibility maintenance problem (VMP) for a
leader-follower pair of Dubins-like vehicles with input constraints, and
proposes an original solution based on the notion of controlled invariance. The
nonlinear model describing the relative dynamics of the vehicles is interpreted
as linear uncertain system, with the leader robot acting as an external
disturbance. The VMP is then reformulated as a linear constrained regulation
problem with additive disturbances (DLCRP).
In this paper we study the strengths and limitations of collaborative teams
of simple agents. In particular, we discuss the efficient use of "ant robots"
for covering a connected region on the Z^{2} grid, whose area is unknown in
advance, and which expands at a given rate, where $n$ is the initial size of
the connected region.
We show that regardless of the algorithm used, and the robots' hardware and
software specifications, the minimal number of robots required in order for
such coverage to be possible is \Omega({\sqrt{n}}).
Whereas classical multi-agent systems have the agent in center, there have
recently been a development towards focusing more on the organization of the
system. This allows the designer to focus on what the system goals are, without
considering how the goals should be fulfilled. This paper investigates whether
taking this approach has any clear advantages to the classical way of
implementing multi-agent systems. The investigation is done by implementing
each type of system in the same environment in order to realize what advantages
and disadvantages each approach has.
Since many of the currently available multi-agent frameworks are generally
mostly intended for research, it can be difficult to built multi-agent systems
using physical robots. In this report I describe a way to combine the
multi-agent framework Jason, an extended version of the agent-oriented
programming language AgentSpeak, with Lego robots to address this problem. By
extending parts of the Jason reasoning cycle I show how Lego robots are able to
complete tasks such as following lines on a floor and communicating to be able
to avoid obstacles with minimal amount of coding.
We provide a brief description of the Jason-DTU system, including the
methodology, the tools and the team strategy that we plan to use in the agent
contest.
The eigenvalue spectrum of the adjacency matrix of a network is closely
related to the behavior of many dynamical processes run over the network. In
the field of robotics, this spectrum has important implications in many
problems that require some form of distributed coordination within a team of
robots. In this paper, we propose a continuous-time control scheme that
modifies the structure of a position-dependent network of mobile robots so that
it achieves a desired set of adjacency eigenvalues.
This note corrects a pretty serious mistake and some inaccuracies in
"Consensus and cooperation in networked multi-agent systems" by R.
Olfati-Saber, J.A. Fax, and R.M. Murray, published in Vol. 95 of the
Proceedings of the IEEE (2007, No. 1, P. 215-233). It also mentions several
stronger results applicable to the class of problems under consideration and
addresses the issue of priority whose interpretation in the above-mentioned
paper is not exact.
In this paper we study the problem of tracking an object moving randomly
through a network of wireless sensors. Our objective is to devise strategies
for scheduling the sensors to optimize the tradeoff between tracking
performance and energy consumption. We cast the scheduling problem as a
Partially Observable Markov Decision Process (POMDP), where the control actions
correspond to the set of sensors to activate at each time step. Using a
bottom-up approach, we consider different sensing, motion and cost models with
increasing levels of difficulty.
This paper asks a new question: how can we control the collective behavior of
self-organized multi-agent systems? We try to answer the question by proposing
a new notion called 'Soft Control', which keeps the local rule of the existing
agents in the system. We show the feasibility of soft control by a case study.
Consider the simple but typical distributed multi-agent model proposed by
Vicsek et al.
Comparative benefits provided by the basic social strategies including
collectivism and egoism are investigated within the framework of democratic
decision-making. In particular, we study the mechanism of growing "snowball" of
cooperation.
We completely characterize the class of pairwise irresolute social choice
functions that are group-strategyproof according to Kelly's preference
extension using a monotonicity and an independence axiom. The class is narrow
but contains a number of appealing Condorcet extensions such as the
\emph{minimal covering set} and the \emph{bipartisan set}, thereby answering a
question raised independently by Barbera (1977) and Kelly (1977). These
functions furthermore encourage participation and thus do not suffer from the
no-show paradox (under Kelly's extension).
Multi-agent systems where the agents are developed by parties with competing
interests, and where there is no access to an agent's internal state, are often
classified as `open'. The member agents of such systems may inadvertently fail
to, or even deliberately choose not to, conform to the system specification.
Consequently, it is necessary to specify the normative relations that may exist
between the agents, such as permission, obligation, and institutional power.
The specification of open agent systems of this sort is largely seen as a
design-time activity.
A facial recognition system is a computer application for automatically
identifying or verifying a person from a digital image or a video frame from a
video source. One of the way is to do this is by comparing selected facial
features from the image and a facial database.It is typically used in security
systems and can be compared to other biometrics such as fingerprint or eye iris
recognition systems. In this paper we focus on 3-D facial recognition system
and biometric facial recognision system. We do critics on facial recognision
system giving effectiveness and weaknesses.
This paper investigates the effectiveness of creative versus uncreative
leadership using EVOC, an agent-based model of cultural evolution. Each
iteration, each agent in the artificial society invents a new action, or
imitates a neighbor's action. Only the leader's actions can be imitated by all
other agents, referred to as followers. Two measures of creativity were used:
(1) invention-to-imitation ratio, iLeader, which measures how often an agent
invents, and (2) rate of conceptual change, cLeader, which measures how
creative an invention is.
The aim our work is to create virtual humans as intelligent entities, which
includes approximate the maximum as possible the virtual agent animation to the
natural human behavior. In order to accomplish this task, our agent must be
capable to interact with the environment, interacting with objects and other
agents. The virtual agent needs to act as real person, so he should be capable
to extract semantic information from the geometric model of the world where he
is inserted, based on his own perception, and he realizes his own decision.
The Internet has changed the way business is conducted in many ways. For
example, in the field of procurement, the possibility to directly interact with
a trading partner has given rise to new mechanisms in the supply chain
management. One such interactive dynamic procurement, which lets both buyer and
seller software agents bid by potential buyer agents instead of static
procurement by vendors. Dynamic procurement decision could provide the buying
and selling channel to buyer, to avoid occurring condition that seller could
not deliver on the contract promise.
Crisis response requires information intensive efforts utilized for reducing
uncertainty, calculating and comparing costs and benefits, and managing
resources in a fashion beyond those regularly available to handle routine
problems. This paper presents an Artificial Immune Systems (AIS) metaphor for
agent based modeling of crisis response operations. The presented model
proposes integration of hybrid set of aspects (multi-agent systems, built-in
defensive model of AIS, situation management, and intensity-based learning) for
crisis response operations.
We study the asymptotic properties of distributed consensus algorithms over
switching directed random networks. More specifically, we focus on consensus
algorithms over independent and identically distributed, directed random
graphs, where each agent can communicate with any other agent with some
exogenously specified probability. While different aspects of consensus
algorithms over random switching networks have been widely studied, a complete
characterization of the distribution of the asymptotic value for general
\textit{asymmetric} random consensus algorithms remains an open problem.
Agents offer a new and exciting way of understanding the world of work. In
this paper we describe the development of agent-based simulation models,
designed to help to understand the relationship between people management
practices and retail performance. We report on the current development of our
simulation models which includes new features concerning the evolution of
customers over time. To test the features we have conducted a series of
experiments dealing with customer pool sizes, standard and noise reduction
modes, and the spread of customers' word of mouth.
Current approaches to the engineering of space software such as satellite
control systems are based around the development of feedback controllers using
packages such as MatLab's Simulink toolbox. These provide powerful tools for
engineering real time systems that adapt to changes in the environment but are
limited when the controller itself needs to be adapted.
Using virtual stock markets with artificial interacting software investors,
aka agent-based models (ABMs), we present a method to reverse engineer
real-world financial time series. We model financial markets as made of a large
number of interacting boundedly rational agents. By optimizing the similarity
between the actual data and that generated by the reconstructed virtual stock
market, we obtain parameters and strategies, which reveal some of the inner
workings of the target stock market.
In this paper, we study the dynamics of a viral spreading process in random
geometric graphs (RGG). The spreading of the viral process we consider in this
paper is closely related with the eigenvalues of the adjacency matrix of the
graph. We deduce new explicit expressions for all the moments of the eigenvalue
distribution of the adjacency matrix as a function of the spatial density of
nodes and the radius of connection. We apply these expressions to study the
behavior of the viral infection in an RGG.
In this paper, we investigate synchronization in a small-world network of
coupled nonlinear oscillators. This network is constructed by introducing
random shortcuts in a nearest-neighbors ring. The local stability of the
synchronous state is closely related with the support of the eigenvalue
distribution of the Laplacian matrix of the network.
It is well-known that the eigenvalue spectrum of the Laplacian matrix of a
network contains valuable information about the network structure and the
behavior of many dynamical processes run on it. In this paper, we propose a
fully decentralized algorithm that iteratively modifies the structure of a
network of agents in order to control the moments of the Laplacian eigenvalue
spectrum.
In this paper we present an analysis of the complexities of large group
collaboration and its application to develop detailed requirements for
collaboration schema for Autonomous Systems (AS). These requirements flow from
our development of a framework for collaboration that provides a basis for
designing, supporting and managing complex collaborative systems that can be
applied and tested in various real world settings. We present the concepts of
"collaborative flow" and "working as one" as descriptive expressions of what
good collaborative teamwork can be in such scenarios.
This paper gives an overview of a proposed strategy for the "Cows and
Herders" scenario given in the Multi-Agent Programming Contest 2009. The
strategy is to be implemented using the Jason platform, based on the
agent-oriented programming language Agent-Speak. The paper describes the
agents, their goals and the strategies they should follow.
In the naming game, individuals or agents exchange pairwise local information
in order to communicate about objects in their common environment. The goal of
the game is to reach a consensus about naming these objects. Originally used to
investigate language formation and self-organizing vocabularies, we extend the
classical naming game with a globally shared memory accessible by all agents.
This shared memory can be interpreted as an external source of knowledge like a
book or an Internet site.
We use the notion of a promise to define local trust between agents
possessing autonomous decision-making. An agent is trustworthy if it is
expected that it will keep a promise. This definition satisfies most
commonplace meanings of trust. Reputation is then an estimation of this
expectation value that is passed on from agent to agent.
Information management and retrieval of all the citizen occurs in almost all
the public service functions. Electronic Government system is an emerging trend
in India through which efforts are made to strive maximum safety and security.
Various solutions for this have been proposed like Shibboleth, Public Key
Infrastructure, Smart Cards and Light Weight Directory Access Protocols. Still,
none of these guarantee 100 percent security.
We are exploring the enhancement of models of agent behaviour with more
"human-like" decision making strategies than are presently available. Our
motivation is to developed with a view to as the decision analysis and support
for electric taxi company under the mission of energy saving and reduction of
CO2, in particular car-pool and car-sharing management policies. In order to
achieve the object of decision analysis for user, we provide a human-agents
interactive spatial behaviour to support user making decision real time.
Background: Many different simulation frameworks, in different topics, need
to treat realistic datasets to initialize and calibrate the system. A precise
reproduction of initial states is extremely important to obtain reliable
forecast from the model.
Organizations of Restricted Generality (ORGs) raise important issues for
formalizing norms that require extensions and revisions of previous
foundational work. For example, extension and revision is required of the
fundamental assumption of the Event Calculus:
Time-varying properties hold at particular time-points if they have been
initiated by an action at some earlier time-point, and not terminated by
another action in the meantime.
Recently the dynamic distance potential field (DDPF) was introduced as a
computationally efficient method to make agents in a simulation of pedestrians
move rather on the quickest path than the shortest. It can be considered to be
an estimated-remaining-journey-time-based one-shot dynamic assignment method
for pedestrian route choice on the operational level of dynamics. In this
contribution the method is shortly introduced and the effect of the method on
RiMEA's test case 11 is investigated.
The simulation of vehicular traffic as well as pedestrian dynamics meanwhile
both have a decades long history. The success of this conference series, PED
and others show that the interest in these topics is still strongly increasing.
This contribution deals with a combination of both systems: pedestrians
crossing a street. In a VISSIM simulation for varying demand jam sizes of
vehicles as well as pedestrians and the travel times of the pedestrians are
measured and compared.
The F.A.S.T. model for microscopic simulation of pedestrians was formulated
with the idea of parallelizability and small computation times in general in
mind, but so far it was never demonstrated, if it can in fact be implemented
efficiently for execution on a multi-core or multi-CPU system. In this
contribution results are given on computation times for the F.A.S.T. model on
an eight-core PC.
Bargaining networks model the behavior of a set of players that need to reach
pairwise agreements for making profits. Nash bargaining solutions are special
outcomes of such games that are both stable and balanced. Kleinberg and Tardos
proved a sharp algorithmic characterization of such outcomes, but left open the
problem of how the actual bargaining process converges to them. A partial
answer was provided by Azar et al. who proposed a distributed algorithm for
constructing Nash bargaining solutions, but without polynomial bounds on its
convergence rate.
Submodular functions are an important class of functions in combinatorial
optimization which satisfy the natural properties of decreasing marginal costs.
The study of these functions has led to strong structural properties with
applications in many areas.
Coordination between organizations on strategic, tactical and operation
levels leads to more effective and efficient supply chains. Supply chain
management is increasing day by day in modern enterprises. The environment is
becoming competitive and many enterprises will find it difficult to survive if
they do not make their sourcing, production and distribution more efficient.
Multi-agent supply chain management has recognized as an effective methodology
for supply chain management.
One of the fundamental assumptions in modern microeconomic theory is that
choice should be rationalizable via a binary preference relation. Sen showed
that rationalizability is equivalent to two consistency conditions on choice,
namely $\alpha$ (contraction) and $\gamma$ (expansion). Within the context of
social choice, however, rationalizability and similar notions of consistency
have proved to be highly problematic, as witnessed by a range of impossibility
results, among which Arrow's is the most prominent.
Display advertising has traditionally been sold via guaranteed contracts -- a
guaranteed contract is a deal between a publisher and an advertiser to allocate
a certain number of impressions over a certain period, for a pre-specified
price per impression. However, as spot markets for display ads, such as the
RightMedia Exchange, have grown in prominence, the selection of advertisements
to show on a given page is increasingly being chosen based on price, using an
auction. As the number of participants in the exchange grows, the price of an
impressions becomes a signal of its value.
In this paper, we consider a leader-following consensus problem for networks
of continuous-time integrator agents with a time-varying leader under
measurement noises. We propose a neighbor-based state-estimation protocol for
every agent to track the leader, and time-varying consensus gains are
introduced to attenuate the noises. By combining the tools of stochastic
analysis and algebraic graph theory, we study mean square convergence of this
multi-agent system under directed fixed as well as switching interconnection
topologies.
In this paper, we consider the consensus problem of dynamical multiple agents
that communicate via a directed moving neighborhood random network. Each agent
performs random walk on a weighted directed network. Agents interact with each
other through random unidirectional information flow when they coincide in the
underlying network at a given instant. For such a framework, we present
sufficient conditions for almost sure asymptotic consensus. Some existed
consensus schemes are shown to be reduced versions of the current model.
We view Digital Ecosystems to be the digital counterparts of biological
ecosystems, which are considered to be robust, self-organising and scalable
architectures that can automatically solve complex, dynamic problems.