Smtlink 2.0

TL;DR

Smtlink 2.0 enhances ACL2 by integrating SMT solvers with improved soundness, extensibility, and support for complex types, enabling more reliable and flexible theorem proving workflows.

Contribution

It introduces a modular, verified translation process and supports new data types, significantly improving over the original monolithic implementation.

Findings

Enhanced soundness and extensibility in SMT integration

Support for complex data types like defprod and deflist

Simplified configuration and usage patterns

Abstract

Smtlink is an extension of ACL2 with Satisfiability Modulo Theories (SMT) solvers. We presented an earlier version at ACL2'2015. Smtlink 2.0 makes major improvements over the initial version with respect to soundness, extensibility, ease-of-use, and the range of types and associated theory-solvers supported. Most theorems that one would want to prove using an SMT solver must first be translated to use only the primitive operations supported by the SMT solver -- this translation includes function expansion and type inference. Smtlink 2.0 performs this translation using a sequence of steps performed by verified clause processors and computed hints. These steps are ensured to be sound. The final transliteration from ACL2 to Z3's Python interface requires a trusted clause processor. This is a great improvement in soundness and extensibility over the original Smtlink which was implemented as a single, monolithic, trusted clause processor. Smtlink 2.0 provides support for FTY defprod, deflist, defalist, and defoption types by using Z3's arrays and user-defined data types. We have identified common usage patterns and simplified the configuration and hint information needed to use Smtlink.