Rulifson, J. F. (1971). QA4 programming concepts. Artificial Intelligence Center, SRI International.
The QA4 programming language is designed for the writing of theorem-provers, robot planners, and problem solvers. The language permits the specification of ambiguous, unorganized programs that solve problems mainly through the use of expression transformation programs that are guided by semantic and pragmatic information. This note presents an informal introduction to the unusual programming concepts used in the construction of such problem-solving programs.