Automation for Interactive Proof: First Prototype
Jia Meng, Claire Quigley and L. C. Paulson.
Automation for Interactive Proof: First Prototype. Information and Computation 204 10 (2006), 1575–1596.
Interactive theorem provers require too much effort from their users. We have been developing a system in which... more Interactive theorem provers require too much effort from their users. We have been developing a system in which Isabelle users obtain automatic support from automatic theorem provers (ATPs) such as Vampire and SPASS. An ATP is invoked at suitable points in the interactive session, and any proof found is given to the user in a window displaying an Isar proof script. There are numerous differences between Isabelle (polymorphic higher-order logic with type classes, natural deduction rule format) and classical ATPs (first-order, untyped, and clause form). Many of these differences have been bridged, and a working prototype that uses background processes already provides much of the desired functionality.
Source-level Proof Reconstruction for Interactive Theorem Proving
L. C. Paulson and Kong Woei Susanto.
Source-level Proof Reconstruction for Interactive Theorem Proving. In: Klaus Schneider and Jens Brandt (editors), Theorem Proving in Higher Order Logics (Springer LNCS 4732, 2007), 232–245.
Interactive proof assistants should verify the proofs they receive from automatic theorem provers. Normally this proof... more Interactive proof assistants should verify the proofs they receive from automatic theorem provers. Normally this proof reconstruction takes place internally, forming part of the integration between the two tools. We have implemented source-level proof reconstruction: resolution proofs are automatically translated to Isabelle proof scripts. Each step of a proof is justified by calling Hurd’s Metis prover, which we have ported to Isabelle. A recurrent issue in this project is the treatment of Isabelle’s axiomatic type classes.
Translating Higher-Order Clauses to First-Order Clauses
With Jia Meng.
Translating Higher-Order Clauses to First-Order Clauses. J. Automated Reasoning 40 1 (2008), 35–60.
Interactive provers typically use higher-order logic, while automatic provers typically use first-order logic. In... more Interactive provers typically use higher-order logic, while automatic provers typically use first-order logic. In order to integrate interactive provers with automatic ones, it is necessary to translate higher-order formulae to first-order form. The translation should ideally be both sound and practical. We have investigated several methods of translating function applications, types and λ-abstractions. Omitting some type information improves the success rate, but can be unsound, so the interactive prover must verify the proofs. This paper presents experimental data that compares the translations in respect of their success rates for three automatic provers.
LEO-II — A Cooperative Automatic Theorem Prover for Classical Higher-Order Logic
Christoph Benzmüller, L. C. Paulson, Frank Theiss and Arnaud Fietzke.
LEO-II - A Cooperative Automatic Theorem Prover for Classical Higher-Order Logic. In: Alessandro Armando, Peter Baumgartner, Gilles Dowek (editors), Automated Reasoning-4th International Joint Conference, IJCAR 2008 (Springer LNCS 5195, 2008), 162–170.
LEO-II is a standalone, resolution-based higher-order theorem prover designed for effective cooperation with... more LEO-II is a standalone, resolution-based higher-order theorem prover designed for effective cooperation with specialist provers for natural fragments of higher-order logic. At present LEO-II can cooperate with the first-order automated theorem provers E, SPASS, and Vampire. The improved performance of LEO-II, especially in comparison to its predecessor LEO, is due to several novel features including the exploitation of term sharing and term indexing techniques, support for primitive equality reasoning, and improved heuristics at the calculus level. LEO-II is implemented in Objective Caml and its problem representation language is the new TPTP THF language.
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Seen by:Lightweight Relevance Filtering for Machine-Generated Resolution Problems
With Jia Meng.
J. Applied Logic 7 1 (2009), 41-57.
Irrelevant clauses in resolution problems increase the search space, making proofs hard to find in a reasonable amount... more Irrelevant clauses in resolution problems increase the search space, making proofs hard to find in a reasonable amount of processor time. Simple relevance filtering methods, based on counting symbols in clauses, improve the success rate for a variety of automatic theorem provers. We have designed these techniques as part of a project to link automatic theorem provers to the interactive theorem prover Isabelle. We have tested them for problems involving thousands of clauses, which yield poor results without filtering. Our methods should be applicable to other tasks where the resolution problems are produced mechanically and where completeness is less important than achieving a high success rate with limited processor time.
MetiTarski: An Automatic Theorem Prover for Real-Valued Special Functions
With Behzad Akbarpour.
J. Automated Reasoning 44 3 (2010), 175–205.
Many theorems involving special functions such as ln, exp and sin can be proved automatically by MetiTarski: a... more Many theorems involving special functions such as ln, exp and sin can be proved automatically by MetiTarski: a resolution theorem prover modified to call a decision procedure for the theory of real closed fields. Special functions are approximated by upper and lower bounds, which are typically rational functions derived from Taylor or continued fraction expansions. The decision procedure simplifies clauses by deleting literals that are inconsistent with other algebraic facts. MetiTarski simplifies arithmetic expressions by conversion to a recursive representation, followed by flattening of nested quotients. Applications include verifying hybrid and control systems.
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