Package org.sosy_lab.java_smt.example.nqueens_user_propagator

Class NQueensEnumeratingPropagator

java.lang.Object

org.sosy_lab.java_smt.basicimpl.AbstractUserPropagator

org.sosy_lab.java_smt.example.nqueens_user_propagator.NQueensEnumeratingPropagator

All Implemented Interfaces:

UserPropagator

Direct Known Subclasses:

NQueensConstraintPropagator

public class NQueensEnumeratingPropagator
extends AbstractUserPropagator

This propagator enumerates the solutions of the NQueens problem by raising a conflict whenever the solver finds a model.

Field Summary

Fields

Modifier and Type	Field	Description
protected final Map<BooleanFormula,Boolean>	currentModel
protected final Deque<Integer>	fixedCount
protected final Deque<BooleanFormula>	fixedVariables
protected final Set<Map<BooleanFormula,Integer>>	modelSet

Constructor Summary

Constructors

Constructor	Description
NQueensEnumeratingPropagator()

Method Summary

Modifier and Type	Method	Description
int	getNumOfSolutions()
void	initializeWithBackend(PropagatorBackend backend)	This method is invoked after the user propagator is registered via BasicProverEnvironment.registerUserPropagator(UserPropagator).
void	onFinalCheck()	This callback is invoked when the solver finds a complete satisfying assignment.
void	onKnownValue(BooleanFormula var, boolean value)	This callback is invoked if the solver gets to know the value of a registered expression (UserPropagator.registerExpression(org.sosy_lab.java_smt.api.BooleanFormula)).
void	onPop(int numPoppedLevel)	This callback is invoked when the solver backtracks.
void	onPush()	This callback is invoked whenever the solver creates a new decision level.

Methods inherited from class org.sosy_lab.java_smt.basicimpl.AbstractUserPropagator

getBackend, onDecision, registerExpression

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

fixedCount

protected final Deque<Integer> fixedCount

fixedVariables

protected final Deque<BooleanFormula> fixedVariables

currentModel

protected final Map<BooleanFormula,Boolean> currentModel

modelSet

protected final Set<Map<BooleanFormula,Integer>> modelSet

Constructor Details

NQueensEnumeratingPropagator

public NQueensEnumeratingPropagator()

Method Details

getNumOfSolutions

public int getNumOfSolutions()

onPush

public void onPush()

Description copied from interface: UserPropagator

This callback is invoked whenever the solver creates a new decision level. A user propagator should maintain backtracking points on each push to enable later backtracking.

The onPush or onPop operation refers to internal state of the SMT/SAT solver while running a SAT check. This does not relate to Prover operations in the SMT-based API, such as BasicProverEnvironment.push(org.sosy_lab.java_smt.api.BooleanFormula) or BasicProverEnvironment.pop().

Specified by:

onPush in interface UserPropagator

Overrides:

onPush in class AbstractUserPropagator

onPop

public void onPop(int numPoppedLevel)

Description copied from interface: UserPropagator

This callback is invoked when the solver backtracks. The solver can backtrack multiple levels simultaneously.

The onPush or onPop operation refers to internal state of the SMT/SAT solver while running a SAT check. This does not relate to Prover operations in the SMT-based API, such as BasicProverEnvironment.push(org.sosy_lab.java_smt.api.BooleanFormula) or BasicProverEnvironment.pop().

Specified by:

onPop in interface UserPropagator

Overrides:

onPop in class AbstractUserPropagator

Parameters:

numPoppedLevel - The number of levels to backtrack (~ number of pushes to backtrack).

onFinalCheck

public void onFinalCheck()

Description copied from interface: UserPropagator

This callback is invoked when the solver finds a complete satisfying assignment. The user can check the found model for consistency and potentially raise conflicts via PropagatorBackend.propagateConflict(BooleanFormula[]).

Note: This callback is only invoked if the user propagator enabled it via PropagatorBackend.notifyOnFinalCheck().

Specified by:

onFinalCheck in interface UserPropagator

Overrides:

onFinalCheck in class AbstractUserPropagator

onKnownValue

public void onKnownValue(BooleanFormula var,
 boolean value)

Description copied from interface: UserPropagator

This callback is invoked if the solver gets to know the value of a registered expression (UserPropagator.registerExpression(org.sosy_lab.java_smt.api.BooleanFormula)). Within the callback, the user can raise conflicts via PropagatorBackend.propagateConflict(org.sosy_lab.java_smt.api.BooleanFormula[]), propagate consequences via PropagatorBackend.propagateConsequence(org.sosy_lab.java_smt.api.BooleanFormula[], org.sosy_lab.java_smt.api.BooleanFormula), or influence the solvers decision heuristics via PropagatorBackend.propagateNextDecision(org.sosy_lab.java_smt.api.BooleanFormula, java.util.Optional<java.lang.Boolean>).

The reported value is only known on the current and later push levels, but will get invalidated when backtracking.

Note: This callback is only invoked if the user propagator enabled it via PropagatorBackend.notifyOnKnownValue().

Specified by:

onKnownValue in interface UserPropagator

Overrides:

onKnownValue in class AbstractUserPropagator

Parameters:

var - The expressions whose value is known.

value - The value of the expression.

initializeWithBackend

public void initializeWithBackend(PropagatorBackend backend)

Description copied from interface: UserPropagator

This method is invoked after the user propagator is registered via BasicProverEnvironment.registerUserPropagator(UserPropagator). The user can enable notifications by accessing the provided PropagatorBackend.

Warning: During its lifetime, a user propagator shall only be registered once via BasicProverEnvironment.registerUserPropagator(UserPropagator) for otherwise unexpected errors can occur. Implementations are advised to throw exceptions if this method is called multiple times.

Specified by:

initializeWithBackend in interface UserPropagator

Overrides:

initializeWithBackend in class AbstractUserPropagator