Struct z3::Solver

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pub struct Solver<'ctx> { /* private fields */ }

Expand description

(Incremental) solver, possibly specialized by a particular tactic or logic.

Implementations§

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impl<'ctx> Solver<'ctx>

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pub fn new(ctx: &'ctx Context) -> Solver<'ctx>

Create a new solver. This solver is a “combined solver” that internally uses a non-incremental (solver1) and an incremental solver (solver2). This combined solver changes its behaviour based on how it is used and how its parameters are set.

If the solver is used in a non incremental way (i.e. no calls to Solver::push() or Solver::pop(), and no calls to Solver::assert() or Solver::assert_and_track() after checking satisfiability without an intervening Solver::reset()) then solver1 will be used. This solver will apply Z3’s “default” tactic.

The “default” tactic will attempt to probe the logic used by the assertions and will apply a specialized tactic if one is supported. Otherwise the general (and-then simplify smt) tactic will be used.

If the solver is used in an incremental way then the combined solver will switch to using solver2 (which behaves similarly to the general “smt” tactic).

Note however it is possible to set the solver2_timeout, solver2_unknown, and ignore_solver1 parameters of the combined solver to change its behaviour.

The function Solver::get_model() retrieves a model if the assertions is satisfiable (i.e., the result is SatResult::Sat) and model construction is enabled. The function Solver::get_model() can also be used even if the result is SatResult::Unknown, but the returned model is not guaranteed to satisfy quantified assertions.

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pub fn from_string<T: Into<Vec<u8>>>(&self, source_string: T)

Parse an SMT-LIB2 string with assertions, soft constraints and optimization objectives. Add the parsed constraints and objectives to the solver.

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pub fn new_for_logic<S: Into<Symbol>>( ctx: &'ctx Context, logic: S ) -> Option<Solver<'ctx>>

Create a new solver customized for the given logic. It returns None if the logic is unknown or unsupported.

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pub fn translate<'dest_ctx>( &self, dest: &'dest_ctx Context ) -> Solver<'dest_ctx>

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pub fn get_context(&self) -> &'ctx Context

Get this solver’s context.

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pub fn assert(&self, ast: &Bool<'ctx>)

Assert a constraint into the solver.

The functions Solver::check() and Solver::check_assumptions() should be used to check whether the logical context is consistent or not.

pub fn assert_and_track(&self, ast: &Bool<'ctx>, p: &Bool<'ctx>)

Assert a constraint a into the solver, and track it (in the unsat) core using the Boolean constant p.

This API is an alternative to Solver::check_assumptions() for extracting unsat cores. Both APIs can be used in the same solver. The unsat core will contain a combination of the Boolean variables provided using Solver::assert_and_track() and the Boolean literals provided using Solver::check_assumptions().

pub fn reset(&self)

Remove all assertions from the solver.

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pub fn check(&self) -> SatResult

Check whether the assertions in a given solver are consistent or not.

The function Solver::get_model() retrieves a model if the assertions is satisfiable (i.e., the result is SatResult::Sat) and model construction is enabled. Note that if the call returns SatResult::Unknown, Z3 does not ensure that calls to Solver::get_model() succeed and any models produced in this case are not guaranteed to satisfy the assertions.

The function Solver::get_proof() retrieves a proof if proof generation was enabled when the context was created, and the assertions are unsatisfiable (i.e., the result is SatResult::Unsat).

pub fn check_assumptions(&self, assumptions: &[Bool<'ctx>]) -> SatResult

Check whether the assertions in the given solver and optional assumptions are consistent or not.

The function Solver::get_unsat_core() retrieves the subset of the assumptions used in the unsatisfiability proof produced by Z3.

pub fn get_assertions(&self) -> Vec<Bool<'_>>

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pub fn get_unsat_core(&self) -> Vec<Bool<'ctx>>

Return a subset of the assumptions provided to either the last

Solver::check_assumptions call, or
sequence of Solver::assert_and_track calls followed by a Solver::check call.

These are the assumptions Z3 used in the unsatisfiability proof. Assumptions are available in Z3. They are used to extract unsatisfiable cores. They may be also used to “retract” assumptions. Note that, assumptions are not really “soft constraints”, but they can be used to implement them.

pub fn push(&self)

Create a backtracking point.

The solver contains a stack of assertions.

pub fn pop(&self, n: u32)

Backtrack n backtracking points.

pub fn get_model(&self) -> Option<Model<'ctx>>

Retrieve the model for the last Solver::check() or Solver::check_assumptions().

The error handler is invoked if a model is not available because the commands above were not invoked for the given solver, or if the result was SatResult::Unsat.

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pub fn get_proof(&self) -> Option<impl Ast<'ctx>>

Retrieve the proof for the last Solver::check() or Solver::check_assumptions().

The error handler is invoked if proof generation is not enabled, or if the commands above were not invoked for the given solver, or if the result was different from SatResult::Unsat.