Analsysis by Propagation of Constraints in Elementary Geometry Problem Solving

Unknown author (1976-06)

This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's artificial intelligence research is provided in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014-75-C-0643.

Working Paper

This paper describes GEL, a new geometry theorem prover. GEL is the result of an attempt to transfer the problem solving abilities of the EL electronic circuit analysis program of Sussman and Stallman to the domain of geometric diagrams. Like its ancestor, GEL is based on the concepts of "one-step local deductions" and "macro-elements." The performance of this program raises a number of questions about the efficacy of the approach to geometry theorem proving embodied in GEL, and also illustrates problems relating to algebraic simplification in geometric reasoning.