CENTER Carnegie Mellon UniversityCarnegie Mellon Computer Science DepartmentSchool of Computer Science
Proof Planning for Theorem Provers
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Can computers manipulate high-level ideas to solve problems, as well as they can push symbols and crunch numbers? A "yes" answer to this question would further suggest that perhaps computers can even achieve a kind of understanding in some areas of knowledge. For today's computers, this does not appear to be the case, and some philosophers such as Searle believe that this could never be the case. While we do not assert that our work answers or even addresses the above question, our work has certainly been thoroughly inspired by it. We aim to give a formal treatment of strategies as high-level ideas for problem-solving, and provide a way to view strategies through the lens of complexity theory.

Prima facie, formalizing 'high-level idea' looks like an obviously circular proposition. That is, it seems if a 'high-level idea' is made formal, then it would cease to be merely an idea! An idea is inherently intuitive, and perhaps even vague-this is exactly the kind of object that a computer cannot manipulate. However, the indeterminacy of a process is not an impediment to its formalization. For example, in the definition of a nondeterministic machine, one defines a machine's behavior via a relation between all potential "deterministic" behaviors of the machine. This is the sort of maneuver we are taking. The meaning of a collection of strategies for a computational problem will be tantamount to a partition on the space of instance-solution pairs, admitting certain nice structural and computational properties.

To this end, we are investigating how such a partition may be realized in the domain of theorem-proving. That is, we are considering methods for clustering theorem-proof pairs to see whether or not a simple notion exists that indeed places proofs together based on the similarity of the strategies used. Such a method would be of particular practical value to theorem-provers based on "Proof planning" [1]--theorem-provers which use high-level plans to both guide the search for proofs and produce proofs that are more understandable to a human mathematician--since work has already begun to automatically extract these high-level plans from sets of well-chosen example proofs [2] which are precisely what we aim to produce.

[1] A. Bundy. "The use of explicit plans to guide inductive proofs." In Ninth Conference on Automated Deduction, Lecture Notes in Computer Science, Vol. 203, pp. 111-120, SpringerVerlag, 1988.
[2] M. Jamnik, M. Kerber, M. Pollet and C. Benzmuller. "Automatic learning of proof methods in proof planning." Logic Journal of the IGPL, 11(6):647-674, 2003.

Preliminary Presentation - Matthew Humphrey (ppt) (pdf)
Final Presentation - Matthew Humphrey (ppt) (pdf)
Preliminary Presentation - Brendan Juba (ppt)
Final Presentation - Brendan Juba (ppt)


This material is based upon work supported by National Science Foundation under Grant No. 0122581.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the
National Science Foundation