org.sat4j.tools

Class AbstractOutputSolver

java.lang.Object

org.sat4j.tools.AbstractOutputSolver

All Implemented Interfaces:

Serializable, IProblem, ISolver, RandomAccessModel

Direct Known Subclasses:

DimacsOutputSolver, DimacsStringSolver

public abstract class AbstractOutputSolver
extends Object
implements ISolver

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	firstConstr
protected boolean	fixedNbClauses
protected int	nbclauses
protected int	nbvars

Constructor Summary

Constructors

Constructor and Description
AbstractOutputSolver()

Method Summary

Methods

Modifier and Type	Method and Description
void	addAllClauses(IVec<IVecInt> clauses) Create clauses from a set of set of literals.
IConstr	addBlockingClause(IVecInt literals) Add a clause in order to prevent an assignment to occur.
void	clearLearntClauses() Remove clauses learned during the solving process.
void	expireTimeout() Expire the timeout of the solver.
int[]	findModel() Look for a model satisfying all the clauses available in the problem.
int[]	findModel(IVecInt assumps) Look for a model satisfying all the clauses available in the problem.
String	getLogPrefix()
<S extends ISolverService> SearchListener<S>	getSearchListener() Get the current SearchListener.
ISolver	getSolvingEngine() Retrieve the real engine in case the engine is decorated by one or several decorator.
Map<String,Number>	getStat() To obtain a map of the available statistics from the solver.
int	getTimeout() Useful to check the internal timeout of the solver.
long	getTimeoutMs() Useful to check the internal timeout of the solver.
boolean	isDBSimplificationAllowed() Indicate whether the solver is allowed to simplify the formula by propagating the truth value of top level satisfied variables.
boolean	isSatisfiable() Check the satisfiability of the set of constraints contained inside the solver.
boolean	isSatisfiable(boolean global) Check the satisfiability of the set of constraints contained inside the solver.
boolean	isSatisfiable(IVecInt assumps) Check the satisfiability of the set of constraints contained inside the solver.
boolean	isSatisfiable(IVecInt assumps, boolean global) Check the satisfiability of the set of constraints contained inside the solver.
boolean	isSolverKeptHot() Ask to the solver if it is in "hot" mode, meaning that the heuristics is not reset after call is isSatisfiable().
boolean	isVerbose() To know if the solver is in verbose mode (output allowed) or not.
int[]	model() Provide a model (if any) for a satisfiable formula.
boolean	model(int var) Provide the truth value of a specific variable in the model.
int	nConstraints() To know the number of constraints currently available in the solver.
int	newVar(int howmany) Declare howmany variables in the problem (and thus in the vocabulary), that will be represented using the Dimacs format by integers ranging from 1 to howmany.
int	nVars() To know the number of variables used in the solver as declared by newVar() In case the method newVar() has not been used, the method returns the number of variables used in the solver.
int[]	primeImplicant() Provide a prime implicant, i.e. a set of literal that is sufficient to satisfy all constraints of the problem.
void	printInfos(PrintWriter output, String prefix) To print additional informations regarding the problem.
void	printStat(PrintStream output, String prefix) Display statistics to the given output stream Please use writers instead of stream.
void	printStat(PrintWriter output, String prefix) Display statistics to the given output writer
boolean	removeConstr(IConstr c) Remove a constraint returned by one of the add method from the solver.
boolean	removeSubsumedConstr(IConstr c) Remove a constraint returned by one of the add method from the solver that is subsumed by a constraint already in the solver or to be added to the solver.
void	setDBSimplificationAllowed(boolean status) Set whether the solver is allowed to simplify the formula by propagating the truth value of top level satisfied variables.
void	setKeepSolverHot(boolean value) Changed the behavior of the SAT solver heuristics between successive calls.
void	setLogPrefix(String prefix) Set the prefix used to display information.
<S extends ISolverService> void	setSearchListener(SearchListener<S> sl) Allow the user to hook a listener to the solver to be notified of the main steps of the search process.
void	setTimeout(int t) To set the internal timeout of the solver.
void	setTimeoutMs(long t) To set the internal timeout of the solver.
void	setTimeoutOnConflicts(int count) To set the internal timeout of the solver.
void	setUnitClauseProvider(UnitClauseProvider upl) Allow the solver to ask for unit clauses before each restarts.
void	setVerbose(boolean value) Set the verbosity of the solver
IVecInt	unsatExplanation() Retrieve an explanation of the inconsistency in terms of assumption literals.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.sat4j.specs.ISolver

addAtLeast, addAtMost, addClause, addExactly, modelWithInternalVariables, newVar, nextFreeVarId, printStat, realNumberOfVariables, registerLiteral, reset, setExpectedNumberOfClauses, toString

Methods inherited from interface org.sat4j.specs.IProblem

primeImplicant, printInfos

Field Detail

nbvars

protected int nbvars

nbclauses

protected int nbclauses

fixedNbClauses

protected boolean fixedNbClauses

firstConstr

protected boolean firstConstr

Constructor Detail

AbstractOutputSolver

public AbstractOutputSolver()

Method Detail

removeConstr

public boolean removeConstr(IConstr c)

Description copied from interface: ISolver

Remove a constraint returned by one of the add method from the solver. All learned clauses will be cleared. Current implementation does not handle properly the case of unit clauses.

Specified by:

removeConstr in interface ISolver

Parameters:

c - a constraint returned by one of the add method.

Returns:

true if the constraint was successfully removed.

addAllClauses

public void addAllClauses(IVec<IVecInt> clauses)
                   throws ContradictionException

Description copied from interface: ISolver

Create clauses from a set of set of literals. This is convenient to create in a single call all the clauses (mandatory for the distributed version of the solver). It is mainly a loop to addClause().

Specified by:

addAllClauses in interface ISolver

Parameters:

clauses - a vector of set (VecInt) of literals in the dimacs format. The vector can be reused since the solver is not supposed to keep a reference to that vector.

Throws:

ContradictionException - iff the vector of literals is empty or if it contains only falsified literals after unit propagation

See Also:

ISolver.addClause(IVecInt)

setTimeout

public void setTimeout(int t)

Description copied from interface: ISolver

To set the internal timeout of the solver. When the timeout is reached, a timeout exception is launched by the solver.

Specified by:

setTimeout in interface ISolver

Parameters:

t - the timeout (in s)

setTimeoutMs

public void setTimeoutMs(long t)

Description copied from interface: ISolver

To set the internal timeout of the solver. When the timeout is reached, a timeout exception is launched by the solver.

Specified by:

setTimeoutMs in interface ISolver

Parameters:

t - the timeout (in milliseconds)

getTimeout

public int getTimeout()

Description copied from interface: ISolver

Useful to check the internal timeout of the solver.

Specified by:

getTimeout in interface ISolver

Returns:

the internal timeout of the solver (in seconds)

getTimeoutMs

public long getTimeoutMs()

Description copied from interface: ISolver

Useful to check the internal timeout of the solver.

Specified by:

getTimeoutMs in interface ISolver

Returns:

the internal timeout of the solver (in milliseconds)

Since:

2.1

expireTimeout

public void expireTimeout()

Description copied from interface: ISolver

Expire the timeout of the solver.

Specified by:

expireTimeout in interface ISolver

isSatisfiable

public boolean isSatisfiable(IVecInt assumps,
                    boolean global)
                      throws TimeoutException

Description copied from interface: IProblem

Check the satisfiability of the set of constraints contained inside the solver.

Specified by:

isSatisfiable in interface IProblem

Parameters:

assumps - a set of literals (represented by usual non null integers in Dimacs format).

global - whether that call is part of a global process (i.e. optimization) or not. if (global), the timeout will not be reset between each call.

Returns:

true if the set of constraints is satisfiable when literals are satisfied, else false.

Throws:

TimeoutException

isSatisfiable

public boolean isSatisfiable(boolean global)
                      throws TimeoutException

Description copied from interface: IProblem

Check the satisfiability of the set of constraints contained inside the solver.

Specified by:

isSatisfiable in interface IProblem

Parameters:

global - whether that call is part of a global process (i.e. optimization) or not. if (global), the timeout will not be reset between each call.

Returns:

true if the set of constraints is satisfiable, else false.

Throws:

TimeoutException

printInfos

public void printInfos(PrintWriter output,
              String prefix)

Description copied from interface: IProblem

To print additional informations regarding the problem.

Specified by:

printInfos in interface IProblem

Parameters:

output - the place to print the information

prefix - the prefix to put in front of each line

setTimeoutOnConflicts

public void setTimeoutOnConflicts(int count)

Description copied from interface: ISolver

To set the internal timeout of the solver. When the timeout is reached, a timeout exception is launched by the solver. Here the timeout is given in number of conflicts. That way, the behavior of the solver should be the same across different architecture.

Specified by:

setTimeoutOnConflicts in interface ISolver

Parameters:

count - the timeout (in number of conflicts)

isDBSimplificationAllowed

public boolean isDBSimplificationAllowed()

Description copied from interface: ISolver

Indicate whether the solver is allowed to simplify the formula by propagating the truth value of top level satisfied variables. Note that the solver should not be allowed to perform such simplification when constraint removal is planned.

Specified by:

isDBSimplificationAllowed in interface ISolver

setDBSimplificationAllowed

public void setDBSimplificationAllowed(boolean status)

Description copied from interface: ISolver

Set whether the solver is allowed to simplify the formula by propagating the truth value of top level satisfied variables. Note that the solver should not be allowed to perform such simplification when constraint removal is planned.

Specified by:

setDBSimplificationAllowed in interface ISolver

printStat

public void printStat(PrintStream output,
             String prefix)

Description copied from interface: ISolver

Display statistics to the given output stream Please use writers instead of stream.

Specified by:

printStat in interface ISolver

prefix - the prefix to put in front of each line

See Also:

ISolver.printStat(PrintWriter, String)

printStat

public void printStat(PrintWriter output,
             String prefix)

Description copied from interface: ISolver

Display statistics to the given output writer

Specified by:

printStat in interface ISolver

prefix - the prefix to put in front of each line

getStat

public Map<String,Number> getStat()

Description copied from interface: ISolver

To obtain a map of the available statistics from the solver. Note that some keys might be specific to some solvers.

Specified by:

getStat in interface ISolver

Returns:

a Map with the name of the statistics as key.

clearLearntClauses

public void clearLearntClauses()

Description copied from interface: ISolver

Remove clauses learned during the solving process.

Specified by:

clearLearntClauses in interface ISolver

model

public int[] model()

Description copied from interface: IProblem

Provide a model (if any) for a satisfiable formula. That method should be called AFTER isSatisfiable() or isSatisfiable(IVecInt) if the formula is satisfiable. Else an exception UnsupportedOperationException is launched.

Specified by:

model in interface IProblem

Returns:

a model of the formula as an array of literals to satisfy.

See Also:

IProblem.isSatisfiable(), IProblem.isSatisfiable(IVecInt)

model

public boolean model(int var)

Description copied from interface: RandomAccessModel

Provide the truth value of a specific variable in the model. That method should be called AFTER isSatisfiable() if the formula is satisfiable. Else an exception UnsupportedOperationException is launched.

Specified by:

model in interface RandomAccessModel

Parameters:

var - the variable id in Dimacs format

Returns:

the truth value of that variable in the model

See Also:

#model()

isSatisfiable

public boolean isSatisfiable()
                      throws TimeoutException

Description copied from interface: IProblem

Check the satisfiability of the set of constraints contained inside the solver.

Specified by:

isSatisfiable in interface IProblem

Returns:

true if the set of constraints is satisfiable, else false.

Throws:

TimeoutException

isSatisfiable

public boolean isSatisfiable(IVecInt assumps)
                      throws TimeoutException

Description copied from interface: IProblem

Check the satisfiability of the set of constraints contained inside the solver.

Specified by:

isSatisfiable in interface IProblem

Parameters:

assumps - a set of literals (represented by usual non null integers in Dimacs format).

Returns:

true if the set of constraints is satisfiable when literals are satisfied, else false.

Throws:

TimeoutException

findModel

public int[] findModel()
                throws TimeoutException

Description copied from interface: IProblem

Look for a model satisfying all the clauses available in the problem. It is an alternative to isSatisfiable() and model() methods, as shown in the pseudo-code: if (isSatisfiable()) { return model(); } return null;

Specified by:

findModel in interface IProblem

Returns:

a model of the formula as an array of literals to satisfy, or null if no model is found

Throws:

TimeoutException - if a model cannot be found within the given timeout.

findModel

public int[] findModel(IVecInt assumps)
                throws TimeoutException

Description copied from interface: IProblem

Look for a model satisfying all the clauses available in the problem. It is an alternative to isSatisfiable(IVecInt) and model() methods, as shown in the pseudo-code: if (isSatisfiable(assumpt)) { return model(); } return null;

Specified by:

findModel in interface IProblem

Returns:

a model of the formula as an array of literals to satisfy, or null if no model is found

Throws:

TimeoutException - if a model cannot be found within the given timeout.

removeSubsumedConstr

public boolean removeSubsumedConstr(IConstr c)

Description copied from interface: ISolver

Remove a constraint returned by one of the add method from the solver that is subsumed by a constraint already in the solver or to be added to the solver. Unlike the removeConstr() method, learned clauses will NOT be cleared. That method is expected to be used to remove constraints used in the optimization process. In order to prevent a wrong from the user, the method will only work if the argument is the last constraint added to the solver. An illegal argument exception will be thrown in other cases.

Specified by:

removeSubsumedConstr in interface ISolver

Parameters:

c - a constraint returned by one of the add method. It must be the latest constr added to the solver.

Returns:

true if the constraint was successfully removed.

Since:

2.1

addBlockingClause

public IConstr addBlockingClause(IVecInt literals)
                          throws ContradictionException

Description copied from interface: ISolver

Add a clause in order to prevent an assignment to occur. This happens usually when iterating over models for instance.

Specified by:

addBlockingClause in interface ISolver

Returns:

Throws:

ContradictionException

Since:

2.1

getSearchListener

public <S extends ISolverService> SearchListener<S> getSearchListener()

Description copied from interface: ISolver

Get the current SearchListener.

Specified by:

getSearchListener in interface ISolver

Returns:

a Search Listener.

Since:

2.2

setSearchListener

public <S extends ISolverService> void setSearchListener(SearchListener<S> sl)

Description copied from interface: ISolver

Allow the user to hook a listener to the solver to be notified of the main steps of the search process.

Specified by:

setSearchListener in interface ISolver

Parameters:

sl - a Search Listener.

Since:

2.1

isVerbose

public boolean isVerbose()

Description copied from interface: ISolver

To know if the solver is in verbose mode (output allowed) or not.

Specified by:

isVerbose in interface ISolver

Returns:

true if the solver is verbose.

Since:

2.2

setVerbose

public void setVerbose(boolean value)

Description copied from interface: ISolver

Set the verbosity of the solver

Specified by:

setVerbose in interface ISolver

Parameters:

value - true to allow the solver to output messages on the console, false either.

Since:

2.2

setLogPrefix

public void setLogPrefix(String prefix)

Description copied from interface: ISolver

Set the prefix used to display information.

Specified by:

setLogPrefix in interface ISolver

Parameters:

prefix - the prefix to be in front of each line of text

Since:

2.2

getLogPrefix

public String getLogPrefix()

Specified by:

getLogPrefix in interface ISolver

Returns:

the string used to prefix the output.

Since:

2.2

unsatExplanation

public IVecInt unsatExplanation()

Description copied from interface: ISolver

Retrieve an explanation of the inconsistency in terms of assumption literals. This is only application when isSatisfiable(assumps) is used. Note that !isSatisfiable(assumps)&&assumps.contains(unsatExplanation()) should hold.

Specified by:

unsatExplanation in interface ISolver

Returns:

a subset of the assumptions used when calling isSatisfiable(assumps). Will return null if not applicable (i.e. no assumptions used).

Since:

2.2

See Also:

IProblem.isSatisfiable(IVecInt), IProblem.isSatisfiable(IVecInt, boolean)

primeImplicant

public int[] primeImplicant()

Description copied from interface: IProblem

Provide a prime implicant, i.e. a set of literal that is sufficient to satisfy all constraints of the problem.

Specified by:

primeImplicant in interface IProblem

Returns:

a prime implicant of the formula as an array of literal, Dimacs format.

nConstraints

public int nConstraints()

Description copied from interface: IProblem

To know the number of constraints currently available in the solver. (without taking into account learned constraints).

Specified by:

nConstraints in interface IProblem

Returns:

the number of constraints added to the solver

newVar

public int newVar(int howmany)

Description copied from interface: IProblem

Declare howmany variables in the problem (and thus in the vocabulary), that will be represented using the Dimacs format by integers ranging from 1 to howmany. That feature allows encodings to create additional variables with identifier starting at howmany+1.

Specified by:

newVar in interface IProblem

Parameters:

howmany - number of variables to create

Returns:

the total number of variables available in the solver (the highest variable number)

See Also:

IProblem.nVars()

nVars

public int nVars()

Description copied from interface: IProblem

To know the number of variables used in the solver as declared by newVar() In case the method newVar() has not been used, the method returns the number of variables used in the solver.

Specified by:

nVars in interface IProblem

Returns:

the number of variables created using newVar().

See Also:

IProblem.newVar(int)

isSolverKeptHot

public boolean isSolverKeptHot()

Description copied from interface: ISolver

Ask to the solver if it is in "hot" mode, meaning that the heuristics is not reset after call is isSatisfiable(). This is only useful in case of repeated calls to the solver with same set of variables.

Specified by:

isSolverKeptHot in interface ISolver

Returns:

true iff the solver keep the heuristics value unchanged across calls.

setKeepSolverHot

public void setKeepSolverHot(boolean value)

Description copied from interface: ISolver

Changed the behavior of the SAT solver heuristics between successive calls. If the value is true, then the solver will be "hot" on reuse, i.e. the heuristics will not be reset. Else the heuristics will be reset.

Specified by:

setKeepSolverHot in interface ISolver

Parameters:

value - true to keep the heuristics values across calls, false either.

getSolvingEngine

public ISolver getSolvingEngine()

Description copied from interface: ISolver

Retrieve the real engine in case the engine is decorated by one or several decorator. This can be used for instance to setup the engine, which requires to bypass all the decorators. It is thus safe to downcast the ISolver to an ICDCL interface. We cannot directly return an ICDCL object because we are not on the same abstraction level here.

Specified by:

getSolvingEngine in interface ISolver

Returns:

the solver

setUnitClauseProvider

public void setUnitClauseProvider(UnitClauseProvider upl)

Description copied from interface: ISolver

Allow the solver to ask for unit clauses before each restarts.

Specified by:

setUnitClauseProvider in interface ISolver

Parameters:

upl - an object able to provide unit clauses.