org.sat4j.pb.constraints.pb

Class MinWatchPb

java.lang.Object

org.sat4j.pb.constraints.pb.WatchPb

org.sat4j.pb.constraints.pb.MinWatchPb

All Implemented Interfaces:

Serializable, Undoable, IWatchPb, PBConstr, Constr, IConstr, Propagatable

Direct Known Subclasses:

PuebloMinWatchPb

public class MinWatchPb
extends WatchPb

Data structure for pseudo-boolean constraint with watched literals. All literals are watched. The sum of the literals satisfied or unvalued is always memorized, to detect conflict.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected BigInteger	watchCumul sum of the coefficients of the literals satisfied or unvalued
protected boolean[]	watched is the literal of index i watching the constraint ?
protected int[]	watching indexes of literals watching the constraint
protected int	watchingCount number of literals watching the constraint.

Fields inherited from class org.sat4j.pb.constraints.pb.WatchPb

activity, coefs, degree, learnt, lits, sumcoefs, voc

Fields inherited from interface org.sat4j.specs.Constr

TAUTOLOGY

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	MinWatchPb(ILits voc, IDataStructurePB mpb) Basic constructor for pb constraint a0.x0 + a1.x1 + ... + an.xn >= k This constructor is called for learnt pseudo boolean constraints.
protected	MinWatchPb(ILits voc, int[] lits, BigInteger[] coefs, BigInteger degree, BigInteger sumCoefs) Basic constructor for PB constraint a0.x0 + a1.x1 + ... + an.xn >= k

Method Summary

Modifier and Type	Method and Description
protected void	computePropagation(UnitPropagationListener s)
protected void	computeWatches()
int	getAssertionLevel(IVecInt trail, int decisionLevel)
protected BigInteger	maximalCoefficient(int pIndice) the maximal coefficient for the watched literals
protected int	nbOfWatched() Number of really watched literals.
static MinWatchPb	normalizedMinWatchPbNew(UnitPropagationListener s, ILits voc, int[] lits, BigInteger[] coefs, BigInteger degree, BigInteger sumCoefs) build a pseudo boolean constraint.
static WatchPb	normalizedWatchPbNew(ILits voc, IDataStructurePB mpb) build a pseudo boolean constraint from a specific data structure.
boolean	propagate(UnitPropagationListener s, int p) Propagation of a falsified literal
boolean	propagatePI(MandatoryLiteralListener l, int p)
void	remove(UnitPropagationListener upl) Remove the constraint from the solver
void	undo(int p) this method is called during backtrack
protected BigInteger	updateWatched(BigInteger mc, int pIndice) update arrays watched and watching w.r.t. the propagation of a literal.

Methods inherited from class org.sat4j.pb.constraints.pb.WatchPb

assertConstraint, assertConstraintIfNeeded, calcReason, calcReasonOnTheFly, canBePropagatedMultipleTimes, canBeSatisfiedByCountingLiterals, coefficientsEqualToOne, computeAnImpliedClause, computeLeftSide, computeLeftSide, dump, equals, forwardActivity, get, getActivity, getCoef, getCoefs, getDegree, getLits, getSumCoefs, getVocabulary, hashCode, incActivity, isAssertive, isSatisfiable, isSatisfied, learnt, locked, ppcm, register, requiredNumberOfSatisfiedLiterals, rescaleBy, setActivity, setLearnt, simplify, size, slackConstraint, slackConstraint, sort, sort, toConstraint, toString, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

watchCumul

protected BigInteger watchCumul

sum of the coefficients of the literals satisfied or unvalued

watched

protected boolean[] watched

is the literal of index i watching the constraint ?

watching

protected int[] watching

indexes of literals watching the constraint

watchingCount

protected int watchingCount

number of literals watching the constraint. This is the real size of the array watching

Constructor Detail

MinWatchPb

protected MinWatchPb(ILits voc,
                     IDataStructurePB mpb)

Basic constructor for pb constraint a0.x0 + a1.x1 + ... + an.xn >= k This constructor is called for learnt pseudo boolean constraints.

Parameters:

voc - all the possible variables (vocabulary)

mpb - a mutable PB constraint

MinWatchPb

protected MinWatchPb(ILits voc,
                     int[] lits,
                     BigInteger[] coefs,
                     BigInteger degree,
                     BigInteger sumCoefs)

Basic constructor for PB constraint a0.x0 + a1.x1 + ... + an.xn >= k

Parameters:

voc - all the possible variables (vocabulary)

lits - literals of the constraint (x0,x1, ... xn)

coefs - coefficients of the left side of the constraint (a0, a1, ... an)

degree - degree of the constraint (k)

Method Detail

computeWatches

protected void computeWatches()
                       throws ContradictionException

Specified by:

computeWatches in class WatchPb

Throws:

ContradictionException

computePropagation

protected void computePropagation(UnitPropagationListener s)
                           throws ContradictionException

Specified by:

computePropagation in class WatchPb

Throws:

ContradictionException

normalizedMinWatchPbNew

public static MinWatchPb normalizedMinWatchPbNew(UnitPropagationListener s,
                                                 ILits voc,
                                                 int[] lits,
                                                 BigInteger[] coefs,
                                                 BigInteger degree,
                                                 BigInteger sumCoefs)
                                          throws ContradictionException

build a pseudo boolean constraint. Coefficients are positive integers less than or equal to the degree (this is called a normalized constraint).

Parameters:

s - a unit propagation listener

voc - the vocabulary

lits - the literals

coefs - the coefficients

degree - the degree of the constraint to normalize.

Returns:

a new PB constraint or null if a trivial inconsistency is detected.

Throws:

ContradictionException

nbOfWatched

protected int nbOfWatched()

Number of really watched literals. It should return the same value as watchingCount. This method must only be called for assertions.

Returns:

number of watched literals.

propagate

public boolean propagate(UnitPropagationListener s,
                         int p)

Propagation of a falsified literal

Parameters:

s - the solver

p - the propagated literal (it must be falsified)

Returns:

false iff there is a conflict

remove

public void remove(UnitPropagationListener upl)

Remove the constraint from the solver

undo

public void undo(int p)

this method is called during backtrack

Parameters:

p - un unassigned literal

normalizedWatchPbNew

public static WatchPb normalizedWatchPbNew(ILits voc,
                                           IDataStructurePB mpb)

build a pseudo boolean constraint from a specific data structure. For learnt constraints.

Parameters:

s - a unit propagation listener (usually the solver)

mpb - data structure which contains literals of the constraint, coefficients (a0, a1, ... an), and the degree of the constraint (k). The constraint is a "more than" constraint.

Returns:

a new PB constraint or null if a trivial inconsistency is detected.

maximalCoefficient

protected BigInteger maximalCoefficient(int pIndice)

the maximal coefficient for the watched literals

Parameters:

pIndice - propagated literal : its coefficient is excluded from the search of the maximal coefficient

Returns:

the maximal coefficient for the watched literals

updateWatched

protected BigInteger updateWatched(BigInteger mc,
                                   int pIndice)

update arrays watched and watching w.r.t. the propagation of a literal. return the maximal coefficient of the watched literals (could have been changed).

Parameters:

mc - the current maximal coefficient of the watched literals

pIndice - the literal propagated (falsified)

Returns:

the new maximal coefficient of the watched literals

propagatePI

public boolean propagatePI(MandatoryLiteralListener l,
                           int p)

getAssertionLevel

public int getAssertionLevel(IVecInt trail,
                             int decisionLevel)