An expert system for solving retrograde-analysis chess problems

The concern here is with the solution of a specialized form of problem (closely concerned with the game of chess) by means of heuristic methods. Defined is an expert system, RETRO, whose domain of application is retrograde-analysis chess problems. This type of problem, chess logic problems as they are sometimes called, differs from the conventional type of chess problem in that it is concerned only with the past history of the game, and what may be deduced about it. Typically, a (human) solution proceeds by the solver asking himself a series of questions in the form of a Socratic dialogue until a solution emerges. RETRO makes use of a frame-like approach to determine the questions that must be asked to effect a solution. Although RETRO cannot solve any conceivable retrograde-analysis problem, the approach taken has been designed to be of general applicability.