3198208
Heterogeneous Active Agents, I: Semantics
Abstract Over the years, many different agent programming languages have been proposed. In this paper, we propose a concept called Agent Programs using which, the way an agent should act in various situations can be declaratively specified by the creator of that agent. Agent Programs may be built on top of arbitrary pieces of software code and may be used to specify what an agent is obliged to do, what an agent may do, and what an agent may not do. In this paper, we define several successively more sophisticated and epistemically satisfying declarative semantics for agent programs. We further show that agent programs cleanly extend well understood semantics for logic programs, and thus are clearly linked to existing results on logic programming and nonmonotonic reasoning.
18059666
IMPACT: the interactive Maryland platform for agents collaborating together
We describe a platform called IMPACT to support multiagent interactions. The platform provides a set of servers (yellow pages, thesaurus, registration, type, and interface) that facilitate agent interoperability in an application independent manner. In IMPACT agents have an associated set of service descriptions, specifying the services they provide. We develop an HTML-like language for such service descriptions. When an agent wishes to identify another agent that provides a service, the requested service must be matched, using a metric approach, against existing service descriptions. We provide a formal framework within which this may be done, and develop algorithms to compute the k nearest matches, as well as all matches within a given distance from the requested service. We report on experiments evaluating our algorithms with large data sets.
813161
Collaborative Multimedia Systems: Synthesis of Media Objects
When a group {/1,..., l/sub n/} of individuals wishes to collaboratively construct a complex multimedia document, the first requirement is that they be able to manipulate media-objects created by one another. For instance, if individual L/sub j/ wishes to access some media objects present at participant l/sub k/'s site, he must be able to: 1) retrieve this object from across the network, 2) ensure that the object is in a form that is compatible with the viewing/editing resources he has available at his node, and 3) ensure that the object has the desired quality (such as image size and resolution). Furthermore, he must be able to achieve these goals at the lowest possible cost. In this paper, we develop a theory of media objects, and present optimal algorithms for collaborative object sharing/synthesis of the sort envisaged above. We then extend the algorithms to incorporate quality constraints (such as image size) as well as distribution across multiple nodes. The theoretical model is validated by an experimental implementation that supports the theoretical results.
18315365
Towards a theory of collaborative multimedia
We develop a theory of media objects, and present optimal algorithms for collaborative synthesis of media objects. We then extend the algorithms to incorporate quality constraints (such as image size) as well as distribution across multiple nodes. The theoretical model is validated by an experimental implementation that supports the theoretical results.
723151
Secure mediated databases
With the evolution of the information superhighway, there is now an immense amount of information available in a wide variety of databases. Furthermore, users often have the ability to access legacy software packages developed by external sources. However, sometimes both the information provided by a data source, as well as one or more of the functions available through a software package may be sensitive-in such cases, organizations require that access by users be controlled. HERMES (HEterogeneous Reasoning and MEdiator System) is a platform that has been developed at the University of Maryland within which mediators may be designed and implemented. HERMES has already been used for a number of applications. In this paper, we provide a formal model of security in mediated systems. We then develop techniques that are sound and complete and respect security constraints of packages/databases participating in the mediated system. The security constraints described an this paper have been implemented, and we describe the existing implementation.