Doran, J. E.
Attempts to write'intelligent' computer programs have commonly involved the choice for attack of some particular aspect of intelligent behaviour, together with the choice of some relevant task, or range of tasks, which the program must perform. Toda (1962), in a whimsical and illuminating paper, has discussed the problems facing an automaton in a simple artificial environment. The reader may find it illuminating to imagine himself (the automaton) before a screen on which is displayed a complex pattern which changes from time to time (sequence of states). These are: 1. the subjective environment graph (figure 1), 2. the stored graph which is that portion of the subjective environment graph which the automaton has stored in its memory as a result of its experience (figure 2 (b)), and 3. the option graph which is that fragment of the stored graph which the automaton'knows' how to reach (figure 2(c)).
Doran, J. E.
Before discussing in detail an example of a simple heuristic problemsolving program, the Graph Traverser, I shall give an indication of the most important work carried out in this field, stressing the more fundamental ideas. Bobrow (1964) describes a question-answering system for high school algebra word problems'. I shall distinguish four: (1) the external application problem to which the program has been applied; (2) the internal problem which the program generates from the application problem and which it must solve in order to produce a solution to the application problem (this internal problem will be an'idealised' version of the application problem, and will typically vary little from one application to another. It is important to realise that more than one internal problem may be capable of derivation from a given application problem); (3) the strategy which the program uses to solve the internal problem; (4) the translation process from the application problem to the internal problem.