Modeling Complex Domains of Actions and Change
  This paper studies the problem of modeling complex domains of actions and
change within high-level action description languages. We investigate two main
issues of concern: (a) can we represent complex domains that capture together
different problems such as ramifications, non-determinism and concurrency of
actions, at a high-level, close to the given natural ontology of the problem
domain and (b) what features of such a representation can affect, and how, its
computational behaviour. The paper describes the main problems faced in this
representation task and presents the results of an empirical study, carried out
through a series of controlled experiments, to analyze the computational
performance of reasoning in these representations. The experiments compare
different representations obtained, for example, by changing the basic ontology
of the domain or by varying the degree of use of indirect effect laws through
domain constraints. This study has helped to expose the main sources of
computational difficulty in the reasoning and suggest some methodological
guidelines for representing complex domains. Although our work has been carried
out within one particular high-level description language, we believe that the
results, especially those that relate to the problems of representation, are
independent of the specific modeling language.
