An integrated model of problem solver

Abstract The purpose of this paper is to propose an unitary formal model, comprehensive of both the classical state-space and problem-reduction approaches, in order to define a new structure of problem solver. In particular, the model we propose, which is strictly related in its formal aspects to the graphs and AND/OR graphs theory, is primarily intended to allow the problem solver to choose, at each step during the solution process, the best representation for the problem (state-space or problem-reduction) and, hence, the optimal expected search strategy. In the paper, the basic functions and the fundamental structure of a problem solver are first presented. The formal definition of the integrated approach is then introduced, together with explanatory examples, and the new model is critically discussed in detail. The formal notions are globally illustrated by a complete example dealing with all the aspects of the solution process. A problem solver model, based on the new approach, is also proposed. Implementation of systems to support an integrated problem solver and the related linguistic problems are not discussed in the paper.