Ivy: A Preprocessor and Proof Checker for First-Order Logic

Abstract

This case study shows how non-ACL2 programs can be combined with ACL2 functions in such a way that useful properties can be proved about the composite programs. Nothing is proved about the non-ACL2 programs Instead, the results of the non-ACL2 programs are checked at run time by ACL2 functions, and properties of these checker functions are proved. The application is resolution/paramodulation automated theorem proving for first-order logic. The top ACL2 function takes a conjecture, preprocesses the conjecture, and calls a non-ACL2 program to search for a proof or countermodel. If the non-ACL2 program succeeds, ACL2 functions check the proof or countermodel. The top ACL2 function is proved sound with respect to finite interpretations.