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Research · August 20 – 23, 1973

Boyer and Moore: induction without human hints

In August 1973, at IJCAI in Stanford, Robert Boyer and J Strother Moore of the University of Edinburgh described a program that proves theorems about recursive LISP functions by mathematical induction on its own; among them, that REVERSE is its own inverse and that a particular sorting program is correct. On an ICL 4130 each theorem took 8 seconds on average.

Why it matters

The machine built the induction formula itself for functions it had not seen before: according to the paper, the user supplies the function definitions and nothing more. Proving a program correct, a sort for instance, became a task for the machine with no human hint.

The program takes a LISP expression, runs it in an interpreter and derives an induction formula from the way the interpreter fails; to this it adds simple rewrite rules of LISP and a heuristic for generalising the theorem. According to the paper, the user supplies nothing but the function definitions. The 8-second average was measured on an ICL 4130 in POP-2. Appendix B lists the theorems proved. What the record does not claim: how many theorems the appendix holds; the paper does not count them.

Event record

Event date
August 20, 1973 – August 23, 1973
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Event date
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Sources gathered automatically · September 27, 2026
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evt-0854

The days of the Third International Joint Conference on Artificial Intelligence at Stanford, 20-23 August 1973, per the IJCAI proceedings page; the paper itself is undated. The journal version is Journal of the ACM 22(1), January 1975.

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