Forthcoming Papers

2002 Journal of Logic and Computation  
OM pairs are our proposed framework for the formalization of metareasoning. OM pairs allow us to generate deductively the object theory and/or the metatheory. This is done by imposing, via appropriate reflection rules, the relation we want to hold between the object theory and the metatheory. In a previous paper we have studied the proof theoretic properties of OM pairs. In this paper we study their model theoretic properties, in particular the relation between the models of the metatheory and
more » ... he object theory; and use these results to refine the previous analysis. Two Logical Theories of Plan Recognition W. Wobcke We present a logical approach to plan recognition that builds on Kautz's theory of keyhole plan recognition, defined as the problem of inferring descriptions of high-level plans from a set of descriptions of observed, typically low-level, actions. Kautz's approach is based on a formalization of the structural information contained in an abstraction/decomposition hierarchy of plan schemas: the inferred plans are selected by an observer agent from amongst those that can be generated from this hierarchy. In this paper, we present two logics for plan recognition. The first theory, like Kautz's, is monotonic, meaning that all possible plans compatible with the observations are treated as equally plausible by the observer. The second theory is based on rejecting this simplifying assumption, and is nonmonotonic. To develop this theory, we adapt ideas from belief revision and conditional logic to define plan recognition inference as a nonmonotonic consequence operation based on an observer's plausibility ordering on the possible plans. The logics incorporate a sound and complete theory of temporal intervals based on Allen's approach, enabling the plan recognition agent to handle temporal information relating multiple observations. An underlying motivation for our work is to provide an intuitive semantic interpretation of plans using situation semantics and to interpret plan recognition as inference over courses of events. In the area of agent-based computing there are many proposals for specific system architectures, and a number of proposals for general approaches to building agents. As yet, however, there are comparatively few attempts to relate these together, and even fewer attempts to provide methodologies which relate designs to architectures and then to executable agents. This paper provides a first attempt to address this shortcoming. We propose a general method of specifying logic-based agents, which is based on the use of multi-context systems, and give examples of its use. The resulting specifications can be directly executed, and we discuss an implementation which makes this direct execution possible. Fibring Labelled Deduction Systems J. Rasga, A. Sernadas, C. Sernadas and L. Viganò We give a categorial characterization of how labelled deduction systems for logics with a propositional basis behave under unconstrained fibring and under fibring that is constrained by symbol sharing. At the semantic level, we introduce a general semantics for our systems and then give a categorial characterization of fibring of models. Based on this, we establish the conditions under which our systems are sound and complete with respect to the general semantics for the corresponding logics, and establish requirements on logics and systems so that completeness is preserved by both forms of fibring. 343
doi:10.1093/logcom/12.2.343 fatcat:zwwbtjctevf2dcwnzt7dx2u4ey