We give a comprehensive and unifying survey of the theoretical aspects of Temporal and modal logic.

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Many of the formalisms used in Attribute Value grammar are notational variants of languages of propositional modal logic, and testing whether two Attribute Value descriptions unify amounts to testing for modal satisfiablity. In this paper we put this observation to work. We study the complexity of the satisfiability problem for nine modal languages which mirror different aspects of AVS description formalisms, including the ability to express re-entrancy, the ability to express generalisations, and the ability to express recursive constraints. Two main techniques are used: either Kripke models with desirable properties are constructed, or modalities are used to simulate fragments of Propositional Dynamic Logic. Further possibilities for the application of modal logic in computational linguistics are noted. Attribute Value Structures (AVSs) are probably the most widely used means of representing linguistic structure in current computational linguistics, and the process of unifying...

. There is a growing need for reliable methods of designing correct reactive systems such as computer operating systems and air traffic control systems. It is widely agreed that certain formalisms such as temporal logic, when coupled with automated reasoning support, provide the most effective and reliable means of specifying and ensuring correct behavior of such systems. This paper discusses known complexity and expressiveness results for a number of such logics in common use and describes key technical tools for obtaining essentially optimal mechanical reasoning algorithms. However, the emphasis is on underlying intuitions and broad themes rather than technical intricacies. 1 Introduction There is a growing need for reliable methods of designing correct reactive systems. These systems are characterized by ongoing, typically nonterminating and highly nondeterministic behavior. Examples include operating systems, network protocols, and air traffic control systems. There is w...

Summary. In this chapter we propose a scripting language, called STEP, for embodied agents, in particular for their communicative acts like gestures and postures. Based on the formal semantics of dynamic logic, STEP has a solid semantic foundation, in spite of a rich number of variants of the compositional operators and interaction facilities on worlds. STEP has been implemented in the distributed logic programming language DLP, a tool for the implementation of 3D web agents. In this chapter, we discuss principles of scripting language design for embodied agents and several aspects of the application of STEP. 1

1 In this paper we present a semantics for our approach based on social commitments (SCs) and arguments for conversational agents. More precisely, we propose a logical model based on CTL * and on dynamic logic (DL). Called Commitment and Argument Network, our formal framework based on this approach uses three basic elements: SCs, actions that agents apply to these SCs and arguments that agents use to support their actions. The advantage of this logical model is to bring together all these elements and the relations existing between them within the same framework. Our semantics makes it possible to represent the dynamics of agent communication. It also allows us to establish the important link between SCs as a deontic concept and arguments. CTL * enables us to express the temporal characteristics of SCs and arguments. DL enables us to capture the actions that agents are committed to achieve. 1.

This paper discusses an approach to feature logic called the structural approach. The method consists in first viewing feature structures as models (or relational structures) in the standard model theoretic sense, and then going on to consider various languages that can be interpeted on these structures and the way these languages are interrelated. It will be shown that the structural approach offers...

In this work we address the problem of what a good domain description for reasoning about actions should look like. We establish some postulates concerning this sore spot and point out the problems that arise when they are violated. Such problems can be overcome with the algorithms we propose.

Abstract. The paper discusses how distributed logic programming can be used to define and control the hand gestures of embodied agents in virtual worlds, by using the STEP language as an interface between the constructs of logic programming and the humanoid model defined in VRML. By using this framework, different gesture dictionaries can be defined and variants of a hand gesture, according to dynamically changing factors, can be generated on the fly. The approach is tested on the demanding demonstrator of conducting, providing experience, also on time performance of the animation. 1

In this paper we propose an XML-based markup language, called XSTEP, for embodied agents, based on the scripting language STEP. Thus, XSTEP is the XML-based successor of STEP. STEP is developed on the formal semantics of dynamic logic, and has been implemented in the distributed logic programming language DLP, a tool for the implementation of 3D web agents. In this paper, we discuss the issues of markup language design for embodied agents and several aspects of the implementation and application of XSTEP. Keywords: embodied agents, avatars, humanoids, H-anim, STEP, XSTEP, XML 1