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 Agent Societies


A Multiagent System for Modeling Democratic Elections

AAAI Conferences

We address the problem of simulate democratic elections via a set of competing agents.We propose a logical model based on a set of non-cooperative agents which compete for attracting a maximum number of votes from a population. Each agent builds a set of strategies (formed by the promises, actions and proposals of the agent) used to convince to the potential voters.


Voting Processes in Complex Adaptive Systems to Combine Perspectives of Disparate Social Simulations into a Coherent Picture

AAAI Conferences

If computational social science is to find practical application in informing policy decisions and proportionately analyzing courses of action, then it will have to make progress in the area of composition of social models.  Since a single simulation cannot hold a world of information, policy makers need to switch in and out modules in federations of simulations to test policies against all possible social environments.  Voting processes as they occur in nature, both in the form of cognition in a human mind of disparate world views, and in the form of equilibria seeking coevolution of species, inform how to combine model results externally and deeply, respectively.  These algorithms, which use the same principles of soft computation found in nature, enable any models to mesh together, even if they have different ontologies, or their data conflict, regardless of the degree they overlap.  A whiteboard architecture in which models report in their own ontologies how other models may inform them and what they have to offer other models, is a framework for the arbitrary meshing of social models.


Speech, Gesture, and Space: Investigating Explicit and Implicit Communication in Multi-Human Multi-Robot Collaborations

AAAI Conferences

It has been demonstrated that people have a tendency to adapt both their linguistic representations and physical Communication is often required between agents as they actions in response to those they are interacting with, i.e., attempt to solve collaborative multi-agent tasks. This is they tend to formulate behavior and speech that will be particularly true in conditions in which an agent is working salient and sensible to a collaborating partner (Whittaker alongside a human--clearly, conventional electronic 2003). Collaboration in humans occurs via a process in communication is not feasible in this scenario; rather, these which people align their linguistic representations of the agents, including humans, must take advantage of physical environment allowing for more effective communicative communication in the shared context to confer necessary behavior. This alignment is achieved via a process in information. As an agent observes the actions of the others, which local alignment of environmental representations, it must modify its own behavior accordingly.


Flexible Multi-Robot Formation Control: Partial Formations as Physical Data Structures

AAAI Conferences

Formations are often seen in nature, and bring many benefits for the group as a whole. They can allow a group to explore a large area more effectively, can ease movement of the group through the environment, and can increase group perceptual coverage and increase defensive capabilities, for example. The benefits of any particular formation vary and are obtained from the structure the formation provides. Robotic formations can have similar applications. To date, the techniques used and formations employed in robotic applications are significantly simpler than those seen in nature. Current techniques often require some level of global knowledge, central processing or other unrealistic assumptions. We seek to develop a formation control technique that has as few of these limitations as possible. Each agent under our approach has only local knowledge of the environment, uses no broadcast communication, and can communicate only over a limited range. Formations are achieved by organizing agents into a graph structure, where agents occupying the vertices take on the role of maintaining an appropriate number of agents on each edge, thus preserving the formation's shape and scale. We do not assume a known or static population: the evolving formation acts as a physical data structure to assist in placing and rearranging agents as the population changes. This approach does not require a global coordinate system, fixed positions within the formation, or any single lead agent. All agents within our approach are peers, and any can adopt any role within the formation.


Decentralized Models for Use in a Real-World Personal Assistant Agent Scenario

AAAI Conferences

Many approaches have been introduced for representing and solving multiagent coordination problems. Unfortunately, these methods make assumptions that limit their usefulness when combined with human operators and real-life hardware and software. In this paper, we discuss the problem of using agents in conjunction with human operators to improve coordination as well as possible models that could be used in these problems. Our approach — Space Collaboration via an Agent Network (SCAN) — enables proxy agents to represent each of the stakeholder agencies in a space setting and shows how the SCAN agent network could facilitate collaboration by identifying opportunities and methods of collaboration. We discuss this approach as well as the challenges in extending models to 1) take advantage of human input, 2) deal with the limited and uncertain information that will be present and 3) combat the scalability issues in solution methods for a large number of decentralized agents. As a first step toward providing rich models for these domains, we describe a method to bound the solution quality due to bounded model uncertainty.


GRASP and path-relinking for Coalition Structure Generation

arXiv.org Artificial Intelligence

In Artificial Intelligence with Coalition Structure Generation (CSG) one refers to those cooperative complex problems that require to find an optimal partition, maximising a social welfare, of a set of entities involved in a system into exhaustive and disjoint coalitions. The solution of the CSG problem finds applications in many fields such as Machine Learning (covering machines, clustering), Data Mining (decision tree, discretization), Graph Theory, Natural Language Processing (aggregation), Semantic Web (service composition), and Bioinformatics. The problem of finding the optimal coalition structure is NP-complete. In this paper we present a greedy adaptive search procedure (GRASP) with path-relinking to efficiently search the space of coalition structures. Experiments and comparisons to other algorithms prove the validity of the proposed method in solving this hard combinatorial problem.


Opinions within Media, Power and Gossip

arXiv.org Artificial Intelligence

Despite the increasing diffusion of the Internet technology, TV remains the principal medium of communication. People's perceptions, knowledge, beliefs and opinions about matter of facts get (in)formed through the information reported on by the mass-media. However, a single source of information (and consensus) could be a potential cause of anomalies in the structure and evolution of a society. Hence, as the information available (and the way it is reported) is fundamental for our perceptions and opinions, the definition of conditions allowing for a good information to be disseminated is a pressing challenge. In this paper starting from a report on the last Italian political campaign in 2008, we derive a socio-cognitive computational model of opinion dynamics where agents get informed by different sources of information. Then, a what-if analysis, performed trough simulations on the model's parameters space, is shown. In particular, the scenario implemented includes three main streams of information acquisition, differing in both the contents and the perceived reliability of the messages spread. Agents' internal opinion is updated either by accessing one of the information sources, namely media and experts, or by exchanging information with one another. They are also endowed with cognitive mechanisms to accept, reject or partially consider the acquired information.


Replicator Dynamics of Coevolving Networks

AAAI Conferences

We propose a simple model of network co-evolution in a game-dynamical system of interacting agents that play repeated games with their neighbors, and adapt their behaviors and network links based on the outcome of those games. The adaptation is achieved through a simple reinforcement learning scheme. We show that the collective evolution of such a system can be described by appropriately defined replicator dynamics equations. In particular, we suggest an appropriate factorization of the agents strategies thats results in a coupled system of equations characterizing the evolution of both strategies and network structure, and illustrate the framework on two simple examples.


Aspects of Metacognitive Self-Awareness in Maryland Virtual Patient

AAAI Conferences

This paper describes Maryland Virtual Patient (MVP), a simulation and tutoring environment developed to support training cognitive decision making in clinical medicine. MVP is implemented as a society of agents, with one role – that of the trainee – played by a human and other roles played by artificial intelligent agents. In order to make the trainee’s experience as similar as possible to the traditional medical training environment, MVP is implemented as a collection of knowledge-based models of simulated human-like perception, reasoning and action processes. MVP operation involves metacognition: for example, the MVP virtual patient is aware of the physiological state of its body, of its physiological and character traits as well as of lacunae in its knowledge about the world and about language. This self-awareness influences the virtual patient’s reasoning and actions. In this paper we illustrate the role of metacognitive self-awareness in the overall operation of MVP.


Convergence to Equilibria in Plurality Voting

AAAI Conferences

Multi-agent decision problems, in which independent agents have to agree on a joint plan of action or allocation of resources, are central to AI. In such situations, agents' individual preferences over available alternatives may vary, and they may try to reconcile these differences by voting. Based on the fact that agents may have incentives to vote strategically and misreport their real preferences, a number of recent papers have explored different possibilities for avoiding or eliminating such manipulations. In contrast to most prior work, this paper focuses on convergence of strategic behavior to a decision from which no voter will want to deviate. We consider scenarios where voters cannot coordinate their actions, but are allowed to change their vote after observing the current outcome. We focus on the Plurality voting rule, and study the conditions under which this iterative game is guaranteed to converge to a Nash equilibrium (i.e., to a decision that is stable against further unilateral manipulations). We show for the first time how convergence depends on the exact attributes of the game, such as the tie-breaking scheme, and on assumptions regarding agents' weights and strategies.