Struct SolutionGuidedValueSelector

pub struct SolutionGuidedValueSelector<Var, Value, BackUpSelector> { /* private fields */ }

The solution-guided [1] ValueSelector, this method searches around the provided solution.

It does this by saving the values found in the solution and assigning to those values whenever possible, if it is not possible then it will fall back on the provided backup_selector.

Bibliography

[1] E. Demirović, G. Chu, and P. J. Stuckey, ‘Solution-based phase saving for CP: A value-selection heuristic to simulate local search behavior in complete solvers’, in Principles and Practice of Constraint Programming: 24th International Conference, CP 2018, Lille, France, August 27-31, 2018, Proceedings 24, 2018, pp. 99–108.

Implementations

impl<BackupSelector> SolutionGuidedValueSelector<PropositionalVariable, bool, BackupSelector>

where BackupSelector: ValueSelector<PropositionalVariable>,

pub fn new( variables: &[PropositionalVariable], variables_with_initial_value: Vec<(PropositionalVariable, bool)>, backup_selector: BackupSelector, ) -> Self

Trait Implementations

impl<Var: Debug, Value: Debug, BackUpSelector: Debug> Debug for SolutionGuidedValueSelector<Var, Value, BackUpSelector>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<BackupSelector> ValueSelector<PropositionalVariable> for SolutionGuidedValueSelector<PropositionalVariable, bool, BackupSelector>

where BackupSelector: ValueSelector<PropositionalVariable>,

fn select_value( &mut self, context: &mut SelectionContext<'_>, decision_variable: PropositionalVariable, ) -> Predicate

Determines which value in the domain of decision_variable to branch next on. The domain of the decision_variable variable should have at least 2 values in it (as it otherwise should not have been selected as decision_variable). Returns a Predicate specifying the required change in the domain.

fn on_solution(&mut self, solution: SolutionReference<'_>)

This method is called when a solution is found; either when iterating over all solutions in the case of a satisfiable problem or on solutions of increasing quality when solving an optimisation problem.

fn is_restart_pointless(&mut self) -> bool

This method returns whether a restart is currently pointless for the ValueSelector.

fn on_unassign_literal(&mut self, _literal: Literal)

A function which is called after a Literal is unassigned during backtracking (i.e. when it was fixed but is no longer), specifically, it provides literal which is the Literal which has been reset. This method could thus be called multiple times in a single backtracking operation by the solver.

fn on_unassign_integer(&mut self, _variable: DomainId, _value: i32)

A function which is called after a DomainId is unassigned during backtracking (i.e. when it was fixed but is no longer), specifically, it provides variable which is the DomainId which has been reset and value which is the value to which the variable was previously fixed. This method could thus be called multiple times in a single backtracking operation by the solver.