As part of an effort to define a unified formal semantics for beliefs, desires and action, this paper sketches a model theory for the axiological aspects of agent theory: hedonic states, likes, goals and values. Particular attention is paid to modelling the intensity of likes. The main intuition underlying the model theory is that the axiological aspects of agent theory can be modelled through computational generalisations of physical dynamics. Computational analogues of force, mass and potential are offered. Introduction An important part of agent theory appears to be the notion of desires. Several formulations of agent theory have adopted beliefs, desires and intentions as a set of basic notions (the so-called BDI models). However, to our knowledge, so far relatively little has been said explicitly in the AI literature about a theory of desires (Cohen and Levesque, 1985 and in press, Moore, 1985a; Kiss, 1988, Shoham, 1989). This paper takes some initial steps towards the explicit f...

. There has been a growing interest in AI in formal, qualitative models of various mental attitudes, starting with the well-researched concepts of knowledge and belief, and continuing with more exotic notions such as goals and intentions. In this initial survey we take stock of the work carried out so far in this field, including the motivation for this line of research, the mental attitudes considered, those not, the (primarily logical) tools used, and some of the outstanding problems. 1 Introduction In this paper we review work on formal, qualitative, explicit models of mental attitudes, as studied in recent years in AI. By `mental attitudes' we mean notions such as knowledge, belief, desires, goals, and so on -- those notions, usually attributed to humans, which are generally associated with people's mental life. We use the term `mental state' to denote the collection of all mental attitudes of an agent. Why does AI care about theories of mental state? To start with, to the extent ...