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JavaSMT

Build Status Build Status on Windows Test Coverage Apache 2.0 License Maven Central

JavaSMT is a common API layer for accessing various SMT solvers. The API is optimized for performance (using JavaSMT has very little runtime overhead compared to using the solver API directly), customizability (features and settings exposed by various solvers should be visible through the wrapping layer) and type-safety (it shouldn't be possible to add boolean terms to integer ones at compile time) sometimes at the cost of verbosity.

Quick links

Getting Started | Documentation | Known Issues | Documentation for Developers | Changelog | Configuration Options

References

Feature overview

JavaSMT can express formulas in the following theories:

  • Integer
  • Rational
  • Bitvector
  • Floating Point
  • Array
  • Uninterpreted Function
  • String and RegEx

The concrete support for a certain theory depends on the underlying SMT solver. Only a few SMT solvers provide support for theories like Arrays, Floating Point, String or RegEx.

Currently JavaSMT supports several SMT solvers (see Getting Started for installation):

SMT Solver Linux64 Windows64 MacOS Description
Boolector ✔️ a fast solver for bitvector logic, misses formula introspection
CVC4 ✔️
MathSAT5 ✔️ ✔️
OptiMathSAT ✔️ same as MathSAT5, but with support for optimization
Princess ✔️ ✔️ ✔️ Java-based SMT solver
SMTInterpol ✔️ ✔️ ✔️ Java-based SMT solver
Yices2 ✔️ soon
Z3 ✔️ ✔️ ✔️ mature and well-known solver

The following features are supported (depending on the used SMT solver):

  • Satisfiability checking
  • Quantifiers and quantifier elimination
  • Incremental solving with assumptions
  • Incremental solving with push/pop
  • Multiple independent contexts
  • Model generation
  • Interpolation, including tree and sequential structure
  • Formula transformation using built-in tactics
  • Formula introspection using visitors

We aim for supporting more important features, more SMT solvers, and more systems. If something specific is missing, please look for or file an issue.

Multithreading Support

SMT Solver Concurrent context usage¹ Concurrent prover usage²
Boolector ✔️
CVC4 ✔️ ✔️
MathSAT5 ✔️
OptiMathSAT ✔️
Princess ✔️
SMTInterpol ✔️
Yices2
Z3 ✔️

Interruption using a ShutdownNotifier may be used to interrupt a a solver from any thread.
Formulas are translatable in between contexts/provers/threads using FormulaManager.translateFrom().

¹ Multiple contexts, but all operations on each context only from a single thread.
² Multiple provers on one or more contexts, with each prover using its own thread.

Garbage Collection in Native Solvers

JavaSMT exposes an API for performing garbage collection on solvers implemented in a native language. As a native solver has no way of knowing whether the created formula object is still referenced by the client application, this API is necessary to avoid leaking memory. Note that several solvers already support hash consing and thus, there is never more than one copy of an identical formula object in memory. Consequently, if all created formulas are later re-used (or re-created) in the application, it is not necessary to perform any garbage collection at all.

Z3

The parameter solver.z3.usePhantomReferences may be used to control whether JavaSMT will attempt to decrease references on Z3 formula objects once they are no longer referenced.

MathSAT5

Currently we do not support performing garbage collection for MathSAT5.

Getting started

Installation is possible via Maven, Ivy, or manually. Please see our Getting Started Guide.

Usage

// Instantiate JavaSMT with SMTInterpol as backend (for dependencies cf. documentation)
try (SolverContext context = SolverContextFactory.createSolverContext(
        config, logger, shutdownNotifier, Solvers.SMTINTERPOL)) {
  IntegerFormulaManager imgr = context.getFormulaManager().getIntegerFormulaManager();

  // Create formula "a = b" with two integer variables
  IntegerFormula a = imgr.makeVariable("a");
  IntegerFormula b = imgr.makeVariable("b");
  BooleanFormula f = imgr.equal(a, b);

  // Solve formula, get model, and print variable assignment
  try (ProverEnvironment prover = context.newProverEnvironment(ProverOptions.GENERATE_MODELS)) {
    prover.addConstraint(f);
    boolean isUnsat = prover.isUnsat();
    assert !isUnsat;
    try (Model model = prover.getModel()) {
      System.out.printf("SAT with a = %s, b = %s", model.evaluate(a), model.evaluate(b));
    }
  }
}

Authors