Agents
How Experience of the Body Shapes Language about Space
Steels, Luc L. (Sony Computer Science Laboratory) | Spranger, Michael (Sony Computer Science Laboratory Paris)
Open-ended language communication remains an enormous challenge for autonomous robots. This paper argues that the notion of a language strategy is the appropriate vehicle for addressing this challenge. A language strategy packages all the procedures that are necessary for playing a language game. We present a specific example of a language strategy for playing an Action Game in which one robot asks another robot to take on a body posture (such as stand or sit), and show how it effectively allows a population of agents to self-organise a perceptually grounded ontology and a lexicon from scratch, without any human intervention. Next, we show how a new language strategy can arise by exaptation from an existing one, concretely, how the body posture strategy can be exapted to a strategy for playing language games about the spatial position of objects (as in "the bottle stands on the table").
Eliciting Single-Peaked Preferences Using Comparison Queries
Voting is a general method for aggregating the preferences of multiple agents. Each agent ranks all the possible alternatives, and based on this, an aggregate ranking of the alternatives (or at least a winning alternative) is produced. However, when there are many alternatives, it is impractical to simply ask agents to report their complete preferences. Rather, the agents' preferences, or at least the relevant parts thereof, need to be elicited. This is done by asking the agents a (hopefully small) number of simple queries about their preferences, such as comparison queries, which ask an agent to compare two of the alternatives. Prior work on preference elicitation in voting has focused on the case of unrestricted preferences. It has been shown that in this setting, it is sometimes necessary to ask each agent (almost) as many queries as would be required to determine an arbitrary ranking of the alternatives. In contrast, in this paper, we focus on single-peaked preferences. We show that such preferences can be elicited using only a linear number of comparison queries, if either the order with respect to which preferences are single-peaked is known, or at least one other agent's complete preferences are known. We show that using a sublinear number of queries does not suffice. We also consider the case of cardinally single-peaked preferences. For this case, we show that if the alternatives' cardinal positions are known, then an agent's preferences can be elicited using only a logarithmic number of queries; however, we also show that if the cardinal positions are not known, then a sublinear number of queries does not suffice. We present experimental results for all elicitation algorithms. We also consider the problem of only eliciting enough information to determine the aggregate ranking, and show that even for this more modest objective, a sublinear number of queries per agent does not suffice for known ordinal or unknown cardinal positions. Finally, we discuss whether and how these techniques can be applied when preferences are almost single-peaked.
Trust-Based Mechanisms for Robust and Efficient Task Allocation in the Presence of Execution Uncertainty
Ramchurn, S. D., Mezzetti, C., Giovannucci, A., Rodriguez-Aguilar, J. A., Dash, R. K., Jennings, N. R.
Vickrey-Clarke-Groves (VCG) mechanisms are often used to allocate tasks to selfish and rational agents. VCG mechanisms are incentive compatible, direct mechanisms that are efficient (i.e., maximise social utility) and individually rational (i.e., agents prefer to join rather than opt out). However, an important assumption of these mechanisms is that the agents will "always" successfully complete their allocated tasks. Clearly, this assumption is unrealistic in many real-world applications, where agents can, and often do, fail in their endeavours. Moreover, whether an agent is deemed to have failed may be perceived differently by different agents. Such subjective perceptions about an agent's probability of succeeding at a given task are often captured and reasoned about using the notion of "trust". Given this background, in this paper we investigate the design of novel mechanisms that take into account the trust between agents when allocating tasks. Specifically, we develop a new class of mechanisms, called "trust-based mechanisms", that can take into account multiple subjective measures of the probability of an agent succeeding at a given task and produce allocations that maximise social utility, whilst ensuring that no agent obtains a negative utility. We then show that such mechanisms pose a challenging new combinatorial optimisation problem (that is NP-complete), devise a novel representation for solving the problem, and develop an effective integer programming solution (that can solve instances with about 2x10^5 possible allocations in 40 seconds).
Managing Requirement Volatility in an Ontology-Driven Clinical LIMS Using Category Theory. International Journal of Telemedicine and Applications
Shaban-Nejad, Arash, Ormandjieva, Olga, Kassab, Mohamad, Haarslev, Volker
Requirement volatility is an issue in software engineering in general, and in Web-based clinical applications in particular, which often originates from an incomplete knowledge of the domain of interest. With advances in the health science, many features and functionalities need to be added to, or removed from, existing software applications in the biomedical domain. At the same time, the increasing complexity of biomedical systems makes them more difficult to understand, and consequently it is more difficult to define their requirements, which contributes considerably to their volatility. In this paper, we present a novel agentbased approach for analyzing and managing volatile and dynamic requirements in an ontology-driven laboratory information management system (LIMS) designed for Web-based case reporting in medical mycology. The proposed framework is empowered with ontologies and formalized using category theory to provide a deep and common understanding of the 1 functional and nonfunctional requirement hierarchies and their interrelations, and to trace the effects of a change on the conceptual framework. Keywords: LIMS, requirement volatility, requirement change management, ontology, category theory, intelligent agents 1. Introduction The life sciences constitute a challenging domain in knowledge representation. Biological data are highly dynamic, and bioinformatics applications are large and there are complex interrelationships between their elements with various levels of interpretation for each concept. In an ideal situation, the requirements for a software system should be completely and unambiguously determined before design, coding, and testing take place. The complexity of bioinformatics applications and their constant evolution lead to frequent changes in their requirements: often new requirements are added and existing requirements are modified or deleted, causing parts of the software system to be redesigned, deleted, or added. Such changes lead to volatility in the requirements of bioinformatics applications. In this paper, we deal with an important problem of requirements volatility in the context of an ontology-driven clinical laboratory information management system (LIMS)[1, 2].
Considerations on Construction Ontologies
Cicortas, Alexandru, Iordan, Victoria Stana, Fortis, Alexandra Emilia
The paper proposes an analysis on some existent ontologies, in order to point out ways to resolve semantic heterogeneity in information systems. Authors are highlighting the tasks in a Knowledge Acquisiton System and identifying aspects related to the addition of new information to an intelligent system. A solution is proposed, as a combination of ontology reasoning services and natural languages generation. A multi-agent system will be conceived with an extractor agent, a reasoner agent and a competence management agent.
Information Modeling for a Dynamic Representation of an Emergency Situation
Kebair, Fahem, Serin, Frederic
It is therefore difficult to actors to make good decisions in time and to coordinate efficiently their efforts, since they do not have enough knowledge about the situation or they do not have timely information they need. The emergency response is one of the greatest challenges that arise to the society currently. One approach to address this challenge is to develop decision support systems (DSS) that may help improve emergency planners and responders awareness and their decision-making abilities. Moreover the system must anticipate the risk of calamitous events or the evolution of a current crisis. This makes planners warned and prepared permanently to future events. Consequently, they can produce robust plans towards both short-term and long-term goals.
Multiagent Bayesian Forecasting of Time Series with Graphical Models
Xiang, Yang (University of Guelph) | Smith, James (University of Warwick) | Kroes, Jeff (University of Guelph)
Time series are found widely in engineering and science. We study multiagent forecasting in time series, drawing from literature on time series, graphical models, and multiagent systems. Knowledge representation of our agents is based on dynamic multiply sectioned Bayesian networks (DMSBNs), a class of cooperative multiagent graphical models. We propose a method through which agents can perform one-step forecast with exact probabilistic inference. Superior performance of our agents over agents based on dynamic Bayesian networks (DBNs) are demonstrated through experiment.
Dynamic Programming Approximations for Partially Observable Stochastic Games
Kumar, Akshat (University of Massachusetts Amherst) | Zilberstein, Shlomo (University of Massachusetts Amherst)
Partially observable stochastic games (POSGs) provide a rich mathematical framework for planning under uncertainty by a group of agents. However, this modeling advantage comes with a price, namely computation cost. Solving POSGs optimally quickly becomes intractable after a few decision cycles. Our main contribution is to provide bounded approximation techniques which enable us to scale POSG algorithms by several orders of magnitude. We study both the general POSGs and its cooperative counterpart DEC-POMDPs. Experiments on a number of problems confirm the scalability of our approach while still providing useful policies.
Making User-Defined Interactive Game Characters BEHAVE
Heckel, Frederick W. P. (The University of North Carolina at Charlotte) | Youngblood, G. Michael (The University of North Carolina at Charlotte) | Hale, D. Hunter (The University of North Carolina at Charlotte)
With the most resource intensive tasks in games offloaded to special purpose processors, game designers now have the opportunity to build richer characters using more complex AI techniques than have been used in the past. While additional CPU time makes improved AI feasible, better tools for building agents are needed to make good interactive characters a reality. In this paper we present the BEHAVEngine and BehaviorShop which enable the creation of rich interactive characters.
Just-in-Time Backfilling in Multi-Agent Scheduling
Gallagher, Anthony (Carnegie Mellon University) | Hunsberger, Luke (Vassar College) | Smith, Stephen F. (Carnegie Mellon University)
This paper addresses the problem of how a group of agents cooperating on a complex plan with interdependent actions can coordinate their scheduling and execution of those actions, particularly in domains where actions may fail or have uncertain durations. If actions fail (or fail to meet their deadlines), the repercussions for the rest of the team's plan can be dramatic. This paper presents a pro-active strategy, called Just-in-Time Backfilling (JIT-BF), that agents can use to increase the fault tolerance of their interdependent schedules by identifying actions in danger of failing and inserting redundant (or back-up) actions into their schedules. The insertion of redundant actions can be done locally (i.e., by the agent whose action is in danger of failing) or through negotiations with the rest of the team. The computations performed by agents following the JIT-BF strategy depend on probabilistic models of action durations and the ``quality'' achieved by successfully executing actions. The paper presents an experimental evaluation of the JIT-BF strategy within a simulated real-time dynamic environment that demonstrates that teams using the pro-active JIT-BF strategy significantly out-perform teams that rely solely on reactive strategies.