that points the way to a solution of the second. In particular, we present a high-level specification of the practical-reasoning component of an architecture for a resource-bounded rational agent. In this architecture, a major role of the agent's plans is to constrain the amount of further practical

. Description Logics (DLs) are a family of knowledge representation formalisms mainly characterised by constructors to build complex concepts and roles from atomic ones. Expressive role constructors are important in many applications, but can be computationally problematical. We present an algorithm that decides satis ability of the DL ALC extended with transitive and inverse roles, role hierarchies, and qualifying number restrictions. Early experiments indicate that this algorithm is well-suited for implementation. Additionally, we show that ALC extended with just transitive and inverse roles is still in PSpace. Finally, we investigate the limits of decidability for this family of DLs.

� Is reasoning directed towards actions — the process of figuring out what to do: • “Practical reasoning is a matter of weighing conflicting considerations for and against competing options, where the relevant considerations are provided by what the agent desires/values/cares about and what

This paper was written while I was a visiting fellow at the Swedish Collegium for Advanced Study in the Social Sciences. I am extremely grateful to the Collegium for its generous support and hospitality. During the paper’s long gestation, I have learnt a great deal about practical reasoning from

� A simple practical reasoning agent:

Abstract. Cognitive psychology investigates the structural properties of hu-man reasoning. We review some achievements of this kind of research and give a critical evaluation of its methods. CONTENTS

Abstract. In this paper we discuss arguments embodying practical reasoning — arguments as to what it is sensible for someone to do in a given situation. We draw attention to differences between practical reasoning and reasoning about beliefs, and suggest that practical arguments should be treated

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Practical reasoning aims at deciding what actions to perform in light of the goals a rational agent possesses. This has been a topic of interest in both philosophy and artificial intelligence, but these two disciplines have produced very different models of practical reasoning. The purpose

extensive and valuable work on the concepts of presumption and practical reasoning. However, Walton’s attempt to model practical reasoning as presumptive is misguided. The notions of “inference ” and of the burden of proof shifting back and forth between proponent and respondent are misleading