SMT Lean

This project is inspired by SMTCoq and aims to provide Lean tactics that discharge goals into SMT solvers. It is under active development and is currently in a beta phase. While it is ready for use, it is important to note that there are still some rough edges and ongoing improvements being made.

Supported Theories

lean-smt currently supports the theories of Uninterpreted Functions and Linear Integer/Real Arithmetic with quantifiers. Mathlib is currently required for Arithmetic. Support for the theory of Bitvectors is at an experimental stage. We are working on adding support for other theories as well.


lean-smt depends on lean-cvc5 FFI, which currently only supports Linux (x86_64) and macOS (AArch64).


To use lean-smt in your project, add the following line to your list of dependencies in lakefile.lean:

require smt from git ""@"main"

lean-smt comes with one main tactic, smt, that translates the current goal into an SMT query, sends the query to cvc5, and (if the solver returns unsat) replays cvc5's proof in Lean. cvc5's proofs sometimes contain holes, which are sent back to the user as Lean goals. The user can then fill in these holes manually or by using other tactics.


To use the smt tactic, you just need to import the Smt library:

import Smt

example {U : Type} [Nonempty U] {f : U → U → U} {a b c d : U}
  (h0 : a = b) (h1 : c = d) (h2 : p1 ∧ True) (h3 : (¬ p1) ∨ (p2 ∧ p3))
  (h4 : (¬ p3) ∨ (¬ (f a c = f b d))) : False := by
  smt [h0, h1, h2, h3, h4]