The Logic Theory Machine

Heuristic search made symbolic theorem proving a concrete computational task.

Allen Newell and Herbert A. Simon

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The contribution

This report describes a program that searched for proofs in symbolic logic. It used heuristics to select promising lines of reasoning rather than exhaustively enumerating every possibility, illustrating an early approach to automated problem solving.

What this does not establish

Its achievements concerned a restricted formal problem domain. They did not demonstrate unrestricted reasoning about the everyday world.

Why this date?

The linked RAND report is dated 12 July 1956.

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The original work

The Logic Theory Machine

Authors: Allen Newell and Herbert A. Simon
Publication: RAND report P-868
Source type: Research report

Original report scan (PDF)

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Cited By

Atlas entries that reference this system. The related 1957 papers are identified below; these are not direct citations to the 1956 report.

Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I (1960)
Related paper about this system. Reference 2 cites Newell and Shaw, Programming the logic theory machine (1957), a separate paper about this system, rather than the 1956 RAND report. Check the reference list.
SIR: A Computer Program for Semantic Information Retrieval (1964)
Related paper about this system. Page 117 discusses Newell and Simon's Logic Theorist. Reference 27 on page 144 cites Empirical Explorations of the Logic Theory Machine: A Case Study in Heuristics (1957), a separate paper from the 1956 RAND report. Check the reference list. Read the source passage.
The Use of Theorem-Proving Techniques in Question-Answering Systems (1968)
Related paper about this system. Page 173 compares VFIND's backward-chaining heuristic with the Logic Theory Machine. Reference 19 on page 181 cites Empirical Explorations of the Logic Theory Machine: A Case Study in Heuristics (1957), a separate paper from the 1956 RAND report. Check the reference list. Read the source passage.

Citations

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Bibliography coverage: Reference section indexed. Open the source.

The 64-page RAND P-868 scan was processed with OCR. This report has bibliographical footnotes rather than a terminal bibliography. The three external works in footnotes 2 and 5 are indexed, with the source images checked; internal references, acknowledgments and report-date statements are excluded.

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Bibliographical footnotes (PDF pages 5, 10)

Footnote 2 (printed page 3): B. V. Bowden (ed.), Faster Than Thought (London: Pitman, 1953), pp. 181-198. Footnote 5 (printed page 8): A. N. Whitehead and Bertrand Russell, Principia Mathematica, vol. I, 2nd edition (Cambridge: 1925). Footnote 5 (printed page 8): D. Hilbert and W. Ackermann, Principles of Mathematical Logic (New York: Chelsea, 1950), Chapter I.

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These links cover verified matches within the Atlas. They are not total scholarly citation counts. A citation alone does not establish that the later system implements the same method.

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The contribution

What this does not establish

Why this date?

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