Derksen, J., Rulifson, J. F., & Waldinger, R. J. (1972, December). The QA4 language applied to robot planning. In Proceedings of the December 5-7, 1972, fall joint computer conference, part II (pp. 1181-1192).
This paper introduces the first implemented version of the problem solving language QA4 and illustrates the application of this language to some simple robot planning problems. Features of the language include built-in backtracking, parallel processing, pattern matching, and set manipulation. Some of these features are described in detail by close examination of the working of one of the robot problems. The QA4 language is intended for use in research aimed at the automatic verification, modification, and synthesis of computer programs and for semantically oriented theorem proving, as well as for robot planning as described in this paper.