3474917
Agent aided aircraft maintenance
Aircraft maintenance is performed by mechanics who are required, by regulation, to consult expert engineers for repair instructions and approval. In addition to their own experience, these engineers rely on external information sources, which are often inadequately indexed and geographically dispersed. The timely retrieval of this distributed information is vital to the engineers' ability to recommend repair procedures in response to the mechanics' requests. This problem domain is well suited for a multi-agent system: it consists of distributed multi-modal information which is needed by multiple users with diverse preferences. In this paper, we describe an implementation of such a system, using the RETSINA multi-agent architecture. Such an implementation reinforces the importance of multi-agent systems, and in particular the usefulness of the RETSINA infrastructure as a basis for the construction of such systems.
53957
Exploiting Problem Structure for Distributed Constraint Optimization
Distributed constraint optimization imposes considerable complexity in agents’ coordinated search for an optimal solution. However, in many application domains, problems often exhibit special structures that can be exploited to facilitate more efficient problem solving. One of the most recurrent structures involves disparity among subpmblems. We present a coordination mechanism, Anchor&Ascend, for distributed constraint optimization that takes advantage of disparity among subpmblems to efficiently guide distributed local search for global optimality. The coordination mechanism assigns different overlapping subpmblems to agents who must interact and iteratively converge on a solution. In particular, an anchor agent who conducts local best first search to optimize its subsolution interacts with the rest of the agents who perform distributed constraint satisfaction to enforce problem constraints and constraints imposed by the anchor agent. We focus our study on the well-known NP-complete job shop scheduling problem. We define and study two problem structure measures, disparity ratio and disparity composition ratio. We experimentally evaluated the effectiveness of the Anchor&Ascend mechanism on a suite of job shop scheduling problems over a wide range of values of disparity composition. Our experimental results show that (1) considerable advantage can be obtained by explicitly exploiting disparity (2) disparity composition ratio plays a more important role than disparity ratio in finding high quality solution with little computational cost.
2588941
Browsing Schedules - An Agent-Based Approach to Navigating the Semantic Web
The Semantic Web promises to change the way agents navigate, harvest and utilize information on the internet. By providing a structured, distributed representation for expressing concepts and relationships defined by multiple ontologies, it is now possible for agents to read and reason about published knowledge, without the need for scrapers, information agents, and centralized ontologies. Agents can utilize this knowledge to seek and invoke other agents and web services, thus supporting navigation across the Semantic Web. We demonstrate how agents support enhanced navigation within a conference-schedule domain, and present three agent-based services: the RETSINA Calendar Agent, which reasons about schedules marked up on the Semantic Web; the DMA2ICal Translation Agent which provides translation services between schedules grounded in different ontologies, and a Conference Agent that invokes the Calendar Agent.
1816609
DAML-S: Semantic Markup for Web Services
The Semantic Web should enable greater access not only to content but also to services on the Web. Users and software agents should be able to discover, invoke, compose, and monitor Web resources offering particular services and having particular properties. As part of the DARPA Agent Markup Language program, we have begun to develop an ontology of services, called DAML-S, that will make these functionalities possible. In this paper we describe the overall structure of the ontology, the service profile for advertising services, and the process model for the detailed description of the operation of services. We also compare DAML-S with several industry efforts to define standards for characterizing services on the Web.
8965477
Configuration management for multi-agent systems
As heterogeneous distributed systems, multi-agent systems present some challenging configuration management issues. There are the problems of knowing how to allocate agents to computers, launch them on remote hosts, and once the agents have been launched, how to monitor their runtime status so as to manage computing resources effectively.
In this paper, we present the RETSINA Configuration Manager, \emph{RECoMa}. We describe its architecture, how it uses agent infrastructure such as service discovery, to assist the multi-agent system administrator in allocating, launching, and monitoring a heterogeneous distributed agent system in a distributed and networked computing environment.\footnote{The authors would like to acknowledge the significant contributions of Matthew W. Easterday in his earlier and exhaustive implementations of configuration management programs and CM design proposals. This research has been sponsored in part by DARPA Grant F-30602-98-2-0138 and the Office of Naval Research Grant N-00014-96-16-1-1222.}
31490698
Cloning for Intelligent Adaptive Information Agents
Adaptation in open, multi-agent information gathering systems is important for several reasons. These reasons include the inability to accurately predict future problem-solving workloads, future changes in existing information requests, future failures and additions of agents and data supply resources, and other future task environment characteristic changes that require system reorganization. We are developing a multi-agent financial portfolio management system that must deal with all of these problems. This paper will briefly describe our approaches and solutions at several different levels within the agents: adaptation at the organizational, planning, scheduling, and execution levels. We discuss our solution for execution-level adaptation (“cloning”) in detail, and present empirical evidence backing up the theory behind this execution-level solution.
1115801
Authorization and privacy for semantic Web services
Web services will soon handle users' private information. They'll need to provide privacy guarantees to prevent this delicate information from ending up in the wrong hands. More generally, Web services will need to reason about their users' policies that specify who can access private information and under what conditions. These requirements are even more stringent for semantic Web services that exploit the semantic Web to automate their discovery and interaction because they must autonomously decide what information to exchange and how. In our previous work, we proposed ontologies for modeling the high-level security requirements and capabilities of Web services and clients.1 This modeling helps to match a client's request with appropriate services-those based on security criteria as well as functional descriptions.
13216385
Multiagent Systems
Agent-based systems technology has generated lots of excitement in recent years because of its promise as a new paradigm for conceptualizing, designing, and implementing software systems. This promise is particularly attractive for creating software that operates in environments that are distributed and open, such as the internet Currently, the great majority of agent-based systems consist of a single agent However as the technology matures and addresses increasingly complex applications, the need for systems that consist of multiple agents that communicate in a peer-to-peer fashion is becoming apparent. Central to the design and effective operation of such multiagent systems (MASs) are a core set of issues and research questions that have been studied over the years by the distributed AI community. In this article, I present some of the critical notions in MASs and the research work that has addressed themI organize these notions around the concept of problem-solving coherence, which I believe is one of the most critical overall characteristics that an MAS should exhibit
2746951
Cost-Sensitive Access Control for Illegitimate Confidential Access by Insiders
In many organizations, it is common to control access to confidential information based on the need-to-know principle; The requests for access are authorized only if the content of the requested information is relevant to the requester’s current information analysis project. We formulate such content-based authorization, i.e. whether to accept or reject access requests as a binary classification problem. In contrast to the conventional error-minimizing classification, we handle this problem in a cost-sensitive learning framework in which the cost caused by incorrect decision is different according to the relative importance of the requested information. In particular, the cost (i.e., damaging effect) for a false positive (i.e., accepting an illegitimate request) is more expensive than that of false negative (i.e., rejecting a valid request). The former is a serious security problem because confidential information, which should not be revealed, can be accessed. From the comparison of the cost-sensitive classifiers with error-minimizing classifiers, we found that the costing with a logistic regression showed the best performance, in terms of the smallest cost paid, the lowest false positive rate, and the relatively low false negative rate.