Recent years have witnessed the birth of a new paradigm for learning environments: animated pedagogical agents. These lifelike autonomous characters cohabit learning environments with students to create rich, face-to-face learning interactions. This opens up exciting new possibilities; for example, agents can demonstrate complex tasks, employ locomotion and gesture to focus students'attention on the most salient aspect of the task at hand, and convey emotional responses to the tutorial situation. Animated pedagogical agents offer great promise for broadening the bandwidth of tutorial communication and increasing learning environments' ability to engage and motivate students. This article sets forth the motivations behind animated pedagogical agents, describes the key capabilities they offer, and discusses the technical issues they raise. The discussion is illustrated with descriptions of a number of animated agents that represent the current state of the art.

... this paper, we argue that, to handle explanation dialogues successfully, a discourse model must include information about the intended effect of individual parts of the text on the hearer, as well as how the parts relate to one another rhetorically. We present a text planner that records this information and show how the resulting structure is used to respond appropriately to a follow-up question.

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This paper gives an overview about the development of the field of Knowledge Engineering over the last 15 years. We discuss the paradigm shift from a transfer view to a modeling view and describe two approaches which considerably shaped research in Knowledge Engineering: Role-limiting Methods and Generic Tasks. To illustrate various concepts and methods which evolved in the last years we describe three modeling frameworks: CommonKADS, MIKE, and PROTG-II. This description is supplemented by discussing some important methodological developments in more detail: specification languages for knowledge-based systems, problem-solving methods, and ontologies. We conclude with outlining the relationship of Knowledge Engineering to Software Engineering, Information Integration and Knowledge Management.

Problem-solving methods provide reusable architectures and components for implementing the reasoning part of knowledge-based systems.

: To create more powerful knowledge acquisition systems, we not only need better acquisition tools, but we need to change the architecture of the knowledge based systems we create so that their structure will provide better support for acquisition. Current acquisition tools permit users to modify factual knowledge but they provide limited support for modifying problem solving knowledge. In this paper, we argue that this limitation (and others) stem from the use of incomplete models of problem solving knowledge and inflexible specification of the interdependencies between problem solving and factual knowledge. We describe the EXPECT architecture which addresses these problems by providing an explicit representation for problem solving knowledge and intent. Using this more explicit representation, EXPECT can automatically derive the interdependencies between problem solving and factual knowledge. By deriving these interdependencies from the structure of the knowledge-based system itself ...

The role of contextual information in intelligent assistant systems is controversial. In this paper, we start from our experience of Intelligent Assistant System developers to clarify some notions about context and to study the question of context sharing. Moreover, we consider two important aspects of man-machine cooperation, namely explanation generation and incremental knowledge acquisition. Making context explicit in cooperative systems is the key factor for any implementation of these two concepts. Starting from our experience in the development of knowledge-based systems, especially of an interactive system for incident management in subway control, we explain our views about context for the development of intelligent assistant systems.

Intelligent artificial agents need to be able to explain and justify their actions. They must therefore understand the rationales for their own actions. This paper describes a technique for acquiring this understanding, implemented in a multimedia explanation system. The system determines the motivation for a decision by recalling the situation in which the decision was made, and replaying the decision under variants of the original situation. Through experimentation the agent is able to discover what factors led to the decisions, and what alternatives might have been chosen had the situation been slightly different. The agent learns to recognize similar situations where the same decision would be made for the same reasons. This approach is implemented in an artificial fighter pilot that can explain the motivations for its actions, situation assessments, and beliefs. Introduction Intelligent artificial agents need to be able to provide explanations and justifications for the actions t...

This paper explores the explanation of subsumption reasoning in Description Logics that are implemented using normalization methods, focusing on the perspective of knowledge engineers. The notion of explanation is specified using a proof-theoretic framework for presenting the inferences supported in these systems. The problem of overly long explanations is addressed by decomposing them into smaller, independent steps, using the notions of “atomic description” and “atomic justification”. Implementation aspects are explored by considering the design space and some desiderata for explanation modules. This approach has been implemented for the classic knowledge representation system.

We address the problem of causal interpretation of the graphical structure of Bayesian belief networks (BBNs). We review the concept of causality explicated in the domain of structural equations models and show that it is applicable to BBNs. In this view, which we call mechanism-based, causality is defined within models and causal asymmetries arise when mechanisms are placed in the context of a system. We lay the link between structural equations models and BBNs models and formulate the conditions under which the latter can be given causal interpretation. 1 INTRODUCTION Although references to causality permeate everyday scientific practice, the notion of causation has been one of the most controversial subjects in the philosophy of science. Hume's critique that causal connections cannot be observed, and therefore have no empirical basis, strongly influenced the empiricist framework and refocused the concept of causality to scientific models as opposed to reality. A strong attack on ca...