Planning with Incomplete Information

Planning is a natural domain of application for frameworks of reasoning about actions and change. In this paper we study how one such framework, the Language E, can form the basis for planning under (possibly) incomplete information. We define two types of plans: weak and safe plans, and propose a planner, called the E-Planner, which is often able to extend an initial weak plan into a safe plan even though the (explicit) information available is incomplete, e.g. for cases where the initial state is not completely known. The E-Planner is based upon a reformulation of the Language E in argumentation terms and a natural proof theory resulting from the reformulation. It uses an extension of this proof theory by means of abduction for the generation of plans and adopts argumentation-based techniques for extending weak plans into safe plans. We provide representative examples illustrating the behaviour of the E-Planner, in particular for cases where the status of fluents is incompletely known.Comment: Proceedings of the 8th International Workshop on Non-Monotonic Reasoning, April 9-11, 2000, Breckenridge, Colorad

A Survey of Trust in Internet Applications

Trust is an important aspect of decision making for Intemet applications and particularly influences the specification of security policy i.e. who is authorised to perform actions as well as the techniques needed to manage and implement security to and for the applications. This survey examines the various definitions of trust in the literature and provides a working definition of trust for Intemet applications. The properties of trust relationships are explained and classes of different types of trust identified in the literature are discussed with examples. Some influential examples of trust management systems are described

Modular-E and the role of elaboration tolerance in solving the qualification problem

AbstractWe describe Modular-E (ME), a specialized, model-theoretic logic for reasoning about actions. ME is able to represent non-deterministic domains involving concurrency, static laws (constraints), indirect effects (ramifications), and narrative information in the form of action occurrences and observations along a time line. We give formal results which characterize ME's high degree of modularity and elaboration tolerance, and show how these properties help to separate out, and provide principled solutions to, different aspects of the qualification problem. In particular, we identify the endogenous qualification problem as the problem of properly accounting for highly distributed, and potentially conflicting, causal knowledge when reasoning about the effects of actions. We show how a comprehensive solution to the endogenous qualification problem helps simplify the exogenous qualification problem — the problem of reconciling conflicts between predictions about what should be true at particular times and actual observations. More precisely, we describe how ME is able to use straightforward default reasoning techniques to solve the exogenous qualification problem largely because its robust treatments of the frame, ramification and endogenous qualification problems combine into a particular characteristic of elaboration tolerance that we formally encapsulate as a notion of “free will”

A Simple Declarative Language for Describing Narratives with Actions

We describe a simple declarative language E for describing the effects of a series of action occurrences within a narrative. E is analogous to Gelfond and Lifschitz's Language A and its extensions, but is based on a differentontology. The semantics of E is based on a simple characterisation of persistence which facilitates a modular approach to extending the expressivity of the language. Domain descriptions in A can be translated to equivalent theories in E.Weshowhow, in the context of reasoning about actions, E's narrative-based ontology may be exploited in order to characterise and synthesise two complementary notions of explanation. According to the first notion, explanation may be partly modelled as the process of suitably extending an apparently inconsistent theory written in 1 E so as to establish consistency,thus providing a natural method, in many cases, to account for conflicting sets of information about the domain. According to the second notion, observations m..

A Simple Declarative Language For Describing Narratives With Actions

this paper (August 1995) appeared as a joint Imperial College / University of Cyprus Research Report (Imperial College Research Report Number DoC 95/12) 1

Contract related agents

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