org.sat4j.tools
Class SolverDecorator

java.lang.Object
  org.sat4j.tools.SolverDecorator

All Implemented Interfaces:

java.io.Serializable, IProblem, ISolver

Direct Known Subclasses:

AbstractSelectorVariablesDecorator, GateTranslator, MinCostDecorator, Minimal4CardinalityModel, Minimal4InclusionModel, MinOneDecorator, ModelIterator, PseudoOptDecorator, SingleSolutionDetector, SolutionCounter

public abstract class SolverDecorator
extends java.lang.Object
implements ISolver, java.io.Serializable

The aim of that class is to allow adding dynamic responsabilities to SAT solvers using the Decorator design pattern. The class is abstract because it does not makes sense to use it "as is".

Author:

leberre

See Also:

Serialized Form

Constructor Summary

SolverDecorator(ISolver solver)

Method Summary

void	addAllClauses(IVec<IVecInt> clauses) Create clauses from a set of set of literals.
IConstr	addAtLeast(IVecInt literals, int degree) Create a cardinality constraint of the type "at least n of those literals must be satisfied"
IConstr	addAtMost(IVecInt literals, int degree) Create a cardinality constraint of the type "at most n of those literals must be satisfied"
IConstr	addClause(IVecInt literals) Create a clause from a set of literals The literals are represented by non null integers such that opposite literals a represented by opposite values.
IConstr	addPseudoBoolean(IVecInt literals, IVec<java.math.BigInteger> coeffs, boolean moreThan, java.math.BigInteger degree) Create a Pseudo-Boolean constraint of the type "at least n of those literals must be satisfied"
void	clearLearntClauses()
ISolver	decorated()
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.
java.util.Map<java.lang.String,java.lang.Number>	getStat() To obtain a map of the available statistics from the solver.
int	getTimeout() Useful to check the internal timeout of the solver.
boolean	isSatisfiable() 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.
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() Create a new variable in the solver (and thus in the vocabulary).
int	newVar(int howmany) Create howmany variables in the solver (and thus in the vocabulary).
int	nVars() To know the number of variables used in the solver.
void	printStat(java.io.PrintStream out, java.lang.String prefix) Deprecated.
void	printStat(java.io.PrintWriter out, java.lang.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.
void	reset() Clean up the internal state of the solver.
void	setExpectedNumberOfClauses(int nb) To inform the solver of the expected number of clauses to read.
void	setTimeout(int t) To set the internal timeout of the solver.
void	setTimeoutMs(long t) To set the internal timeout of the solver.
java.lang.String	toString(java.lang.String prefix) Display a textual representation of the solver configuration.

Methods inherited from class java.lang.Object

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

Constructor Detail

SolverDecorator

public SolverDecorator(ISolver solver)

Method Detail

clearLearntClauses

public void clearLearntClauses()

Specified by:

clearLearntClauses in interface ISolver

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.

model

public boolean model(int var)

Description copied from interface: IProblem

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 IProblem

Parameters:

var - the variable id in Dimacs format

Returns:

the truth value of that variable in the model

See Also:

IProblem.model()

setExpectedNumberOfClauses

public void setExpectedNumberOfClauses(int nb)

Description copied from interface: ISolver

To inform the solver of the expected number of clauses to read. This is an optional method, that is called when the p cnf line is read in dimacs formatted input file.

Specified by:

setExpectedNumberOfClauses in interface ISolver

Parameters:

nb - the expected number of clauses.

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 second)

toString

public java.lang.String toString(java.lang.String prefix)

Description copied from interface: ISolver

Display a textual representation of the solver configuration.

Specified by:

toString in interface ISolver

Parameters:

prefix - the prefix to use on each line.

Returns:

a textual description of the solver internals.

printStat

@Deprecated
public void printStat(java.io.PrintStream out,
                                 java.lang.String prefix)

Deprecated.

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(java.io.PrintWriter out,
                      java.lang.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

newVar

public int newVar()

Description copied from interface: ISolver

Create a new variable in the solver (and thus in the vocabulary). WE STRONGLY ENCOURAGE TO PRECOMPUTE THE NUMBER OF VARIABLES NEEDED AND TO USE newVar(howmany) INSTEAD. IF YOU EXPERIENCE A PROBLEM OF EFFICIENCY WHEN READING/BUILDING YOUR SAT INSTANCE, PLEASE CHECK THAT YOU ARE NOT USING THAT METHOD.

Specified by:

newVar in interface ISolver

Returns:

the number of variables available in the vocabulary, which is the identifier of the new variable.

newVar

public int newVar(int howmany)

Description copied from interface: ISolver

Create howmany variables in the solver (and thus in the vocabulary).

Specified by:

newVar in interface ISolver

Parameters:

howmany - number of variables to create

Returns:

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

addClause

public IConstr addClause(IVecInt literals)
                  throws ContradictionException

Description copied from interface: ISolver

Create a clause from a set of literals The literals are represented by non null integers such that opposite literals a represented by opposite values. (clasical Dimacs way of representing literals).

Specified by:

addClause in interface ISolver

Parameters:

literals - a set of literals

Returns:

a reference to the constraint added in the solver, to use in removeConstr().

Throws:

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

See Also:

ISolver.removeConstr(IConstr)

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)

addAtMost

public IConstr addAtMost(IVecInt literals,
                         int degree)
                  throws ContradictionException

Description copied from interface: ISolver

Create a cardinality constraint of the type "at most n of those literals must be satisfied"

Specified by:

addAtMost in interface ISolver

Parameters:

literals - a set of literals The vector can be reused since the solver is not supposed to keep a reference to that vector.

degree - the degree of the cardinality constraint

Returns:

a reference to the constraint added in the solver, to use in removeConstr().

Throws:

ContradictionException - iff the vector of literals is empty or if it contains more than degree satisfied literals after unit propagation

See Also:

ISolver.removeConstr(IConstr)

addAtLeast

public IConstr addAtLeast(IVecInt literals,
                          int degree)
                   throws ContradictionException

Description copied from interface: ISolver

Create a cardinality constraint of the type "at least n of those literals must be satisfied"

Specified by:

addAtLeast in interface ISolver

Parameters:

literals - a set of literals. The vector can be reused since the solver is not supposed to keep a reference to that vector.

degree - the degree of the cardinality constraint

Returns:

a reference to the constraint added in the solver, to use in removeConstr().

Throws:

ContradictionException - iff the vector of literals is empty or if degree literals are not remaining unfalsified after unit propagation

See Also:

ISolver.removeConstr(IConstr)

addPseudoBoolean

public IConstr addPseudoBoolean(IVecInt literals,
                                IVec<java.math.BigInteger> coeffs,
                                boolean moreThan,
                                java.math.BigInteger degree)
                         throws ContradictionException

Description copied from interface: ISolver

Create a Pseudo-Boolean constraint of the type "at least n of those literals must be satisfied"

Specified by:

addPseudoBoolean in interface ISolver

Parameters:

literals - a set of literals. The vector can be reused since the solver is not supposed to keep a reference to that vector.

coeffs - the coefficients of the literals. The vector can be reused since the solver is not supposed to keep a reference to that vector.

moreThan - true if it is a constraint >= degree

degree - the degree of the cardinality constraint

Returns:

a reference to the constraint added in the solver, to use in removeConstr().

Throws:

ContradictionException - iff the vector of literals is empty or if the constraint is falsified after unit propagation

See Also:

ISolver.removeConstr(IConstr)

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)

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

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)

nConstraints

public int nConstraints()

Description copied from interface: IProblem

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

Specified by:

nConstraints in interface IProblem

Returns:

the number of contraints added to the solver

nVars

public int nVars()

Description copied from interface: IProblem

To know the number of variables used in the solver.

Specified by:

nVars in interface IProblem

Returns:

the number of variables created using newVar().

reset

public void reset()

Description copied from interface: ISolver

Clean up the internal state of the solver.

Specified by:

reset in interface ISolver

decorated

public ISolver decorated()

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 learnt clauses will be cleared.

Specified by:

removeConstr in interface ISolver

Parameters:

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

Returns:

true if the constraint was sucessfully removed.

getStat

public java.util.Map<java.lang.String,java.lang.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.