choco.integer.constraints
Class IntLinComb

java.lang.Object
  choco.AbstractEntity
      choco.AbstractConstraint
          choco.integer.constraints.AbstractIntConstraint
              choco.integer.constraints.AbstractLargeIntConstraint
                  choco.integer.constraints.IntLinComb

All Implemented Interfaces:

Constraint, Entity, IntConstraint, IntVarEventListener, VarEventListener, Propagator, java.lang.Cloneable, java.util.EventListener

Direct Known Subclasses:

PalmIntLinComb

public class IntLinComb
extends AbstractLargeIntConstraint

Implements a constraint Sigma (ai Xi) <=/>=/= C, with Xi variables, ai and C search constants.

Field Summary

protected int[]	coeffs Field representing the type of linear constraint (equality, inequality, disequality)
protected int	cste The search constant of the constraint
static int	EQ Constant, to be assigned to op, representing linear equalities
static int	GEQ Constant, to be assigned to op, representing linear inequalities
protected int	nbPosVars Field representing the number of variables with positive coeffficients in the linear combination (all positive coefficients are given before negative ones)
static int	NEQ Constant, to be assigned to op, representing linear disequalities
protected int	op Field representing the type of linear constraint (equality, inequality, disequality)

Fields inherited from class choco.integer.constraints.AbstractLargeIntConstraint

cIndices, vars

Fields inherited from class choco.integer.constraints.AbstractIntConstraint

logger

Fields inherited from class choco.AbstractConstraint

active, constAwakeEvent, hook, priority

Fields inherited from class choco.AbstractEntity

problem

Constructor Summary

IntLinComb(IntDomainVar[] lvars, int[] lcoeffs, int nbPositive, int c, int linOperator)
Constructs the constraint with the specified variables and constant.

Method Summary

void	awakeOnInf(int idx) Default propagation on improved lower bound: propagation on domain revision.
void	awakeOnInst(int idx) Default propagation on instantiation: full constraint re-propagation.
void	awakeOnRem(int idx, int x) Default propagation on one value removal: propagation on domain revision.
void	awakeOnSup(int idx) Default propagation on improved upper bound: propagation on domain revision.
void	awakeOnVar(int idx) Default propagation on variable revision: full constraint re-propagation.
java.lang.Object	clone() returns a copy of the constraint.
protected int	computeLowerBound() computes a lower bound estimate of a linear combination of variables
protected int	computeUpperBound() computes an upper bound estimate of a linear combination of variables
protected void	filter(boolean startWithLB, int minNbRules) a strategy for chaotic iteration with two rules (LB and UB propagation) the fix point is reached individually for each rule in one function call but this call may break the stability condition for the other rule (in which case the second rule infers new information from the fresh inferences made by the first rule).
protected boolean	filterOnImprovedLowerBound()
protected boolean	filterOnImprovedUpperBound()
protected boolean	hasConsistentLowerBound() tests if the constraint is consistent with respect to the current state of domains
protected boolean	hasConsistentUpperBound()
void	init(int[] lcoeffs)
boolean	isConsistent() tests if the constraint is consistent with respect to the current state of domains
java.lang.Boolean	isEntailed() Checks whether the constraint is definitely satisfied, no matter what further restrictions occur to the domain of its variables.
boolean	isEquivalentTo(Constraint compareTo) tests the equivalence (logical equality of the conditions) between two constraints.
boolean	isSatisfied() Semantic: Testing if the constraint is satisfied.
AbstractConstraint	opposite() computes the constraint modelling the counter-opposite condition of this
java.lang.String	pretty() pretty printing of the object.
void	propagate() Propagates the constraint awake events.
protected boolean	propagateNewLowerBound(int mylb) propagates the constraint sigma(ai Xi) + c <= 0 where mylb = sigma(ai inf(Xi)) + c note: this does not reach saturation (fix point), but returns a boolean indicating whether it infered new information or not.
protected boolean	propagateNewUpperBound(int myub) propagates the constraint sigma(ai Xi) + c <= 0 where myub = sigma(ai sup(Xi)) + c note: this does not reach saturation (fix point), but returns a boolean indicating whether it infered new information or not.

Methods inherited from class choco.integer.constraints.AbstractLargeIntConstraint

assignIndices, getConstraintIdx, getIntVar, getNbVars, getVar, isCompletelyInstantiated, setConstraintIndex, setVar

Methods inherited from class choco.integer.constraints.AbstractIntConstraint

awakeOnBounds, awakeOnRemovals, getSelfIndex

Methods inherited from class choco.AbstractConstraint

addListener, awake, connectVar, constAwake, delete, fail, getEvent, getPlugIn, getPriority, getProblem, getVarIdxInOpposite, isActive, setActive, setEntailed, setPassive, setPlugIn, substituteVar

Methods inherited from class java.lang.Object

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

Methods inherited from interface choco.Propagator

awake, constAwake, delete, getEvent, getPlugIn, getPriority

Methods inherited from interface choco.prop.VarEventListener

addListener, isActive, setActive, setPassive

Methods inherited from interface choco.prop.VarEventListener

addListener, isActive, setActive, setPassive

Field Detail

EQ

public static final int EQ

Constant, to be assigned to op, representing linear equalities

See Also:

Constant Field Values

GEQ

public static final int GEQ

Constant, to be assigned to op, representing linear inequalities

See Also:

Constant Field Values

NEQ

public static final int NEQ

Constant, to be assigned to op, representing linear disequalities

See Also:

Constant Field Values

op

protected final int op

Field representing the type of linear constraint (equality, inequality, disequality)

coeffs

protected int[] coeffs

Field representing the type of linear constraint (equality, inequality, disequality)

nbPosVars

protected final int nbPosVars

Field representing the number of variables with positive coeffficients in the linear combination (all positive coefficients are given before negative ones)

cste

protected final int cste

The search constant of the constraint

Constructor Detail

IntLinComb

public IntLinComb(IntDomainVar[] lvars,
                  int[] lcoeffs,
                  int nbPositive,
                  int c,
                  int linOperator)

Constructs the constraint with the specified variables and constant. Use the Problem.createIntLinComb API instead of this constructor. This constructor assumes that there are no null coefficient and that the positive coefficients come before the negative ones.

Method Detail

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Description copied from interface: Constraint

returns a copy of the constraint. This copy is a new object, may be a recursive copy in case of composite constraints. The original and the copy share the same variables & plugins

Specified by:

clone in interface Constraint

Overrides:

clone in class AbstractLargeIntConstraint

Returns:

Throws:

java.lang.CloneNotSupportedException

init

public void init(int[] lcoeffs)

propagate

public void propagate()
               throws ContradictionException

Description copied from class: AbstractLargeIntConstraint

Propagates the constraint awake events.

Specified by:

propagate in interface Propagator

Overrides:

propagate in class AbstractLargeIntConstraint

Throws:

ContradictionException

awakeOnVar

public void awakeOnVar(int idx)
                throws ContradictionException

Description copied from class: AbstractConstraint

Default propagation on variable revision: full constraint re-propagation.

Specified by:

awakeOnVar in interface VarEventListener

Specified by:

awakeOnVar in interface Propagator

Overrides:

awakeOnVar in class AbstractConstraint

Throws:

ContradictionException

awakeOnInf

public void awakeOnInf(int idx)
                throws ContradictionException

Description copied from class: AbstractIntConstraint

Default propagation on improved lower bound: propagation on domain revision.

Specified by:

awakeOnInf in interface IntVarEventListener

Overrides:

awakeOnInf in class AbstractIntConstraint

Throws:

ContradictionException

awakeOnSup

public void awakeOnSup(int idx)
                throws ContradictionException

Description copied from class: AbstractIntConstraint

Default propagation on improved upper bound: propagation on domain revision.

Specified by:

awakeOnSup in interface IntVarEventListener

Overrides:

awakeOnSup in class AbstractIntConstraint

Throws:

ContradictionException

awakeOnInst

public void awakeOnInst(int idx)
                 throws ContradictionException

Description copied from class: AbstractIntConstraint

Default propagation on instantiation: full constraint re-propagation.

Specified by:

awakeOnInst in interface IntVarEventListener

Overrides:

awakeOnInst in class AbstractIntConstraint

Throws:

ContradictionException

awakeOnRem

public void awakeOnRem(int idx,
                       int x)
                throws ContradictionException

Description copied from class: AbstractIntConstraint

Default propagation on one value removal: propagation on domain revision.

Specified by:

awakeOnRem in interface IntVarEventListener

Overrides:

awakeOnRem in class AbstractIntConstraint

Throws:

ContradictionException

isEntailed

public java.lang.Boolean isEntailed()

Description copied from interface: Propagator

Checks whether the constraint is definitely satisfied, no matter what further restrictions occur to the domain of its variables.

Specified by:

isEntailed in interface Propagator

Overrides:

isEntailed in class AbstractConstraint

isSatisfied

public boolean isSatisfied()

Description copied from interface: Constraint

Semantic: Testing if the constraint is satisfied. Note that all variables involved in the constraint must be instantiated when this method is called.

computeUpperBound

protected int computeUpperBound()

computes an upper bound estimate of a linear combination of variables

computeLowerBound

protected int computeLowerBound()

computes a lower bound estimate of a linear combination of variables

filter

protected void filter(boolean startWithLB,
                      int minNbRules)
               throws ContradictionException

a strategy for chaotic iteration with two rules (LB and UB propagation) the fix point is reached individually for each rule in one function call but this call may break the stability condition for the other rule (in which case the second rule infers new information from the fresh inferences made by the first rule). The algorithm oscilates between both rules until a global fix point is reached.

Parameters:

startWithLB - whether LB must be the first rule applied

minNbRules - minimum number of rules required to reach fiux point.

Throws:

ContradictionException

filterOnImprovedLowerBound

protected boolean filterOnImprovedLowerBound()
                                      throws ContradictionException

Throws:

ContradictionException

filterOnImprovedUpperBound

protected boolean filterOnImprovedUpperBound()
                                      throws ContradictionException

Throws:

ContradictionException

propagateNewLowerBound

protected boolean propagateNewLowerBound(int mylb)
                                  throws ContradictionException

propagates the constraint sigma(ai Xi) + c <= 0 where mylb = sigma(ai inf(Xi)) + c note: this does not reach saturation (fix point), but returns a boolean indicating whether it infered new information or not.

Throws:

ContradictionException

propagateNewUpperBound

protected boolean propagateNewUpperBound(int myub)
                                  throws ContradictionException

propagates the constraint sigma(ai Xi) + c <= 0 where myub = sigma(ai sup(Xi)) + c note: this does not reach saturation (fix point), but returns a boolean indicating whether it infered new information or not.

Throws:

ContradictionException

isConsistent

public boolean isConsistent()

tests if the constraint is consistent with respect to the current state of domains

Specified by:

isConsistent in interface Propagator

Overrides:

isConsistent in class AbstractIntConstraint

Returns:

true iff the constraint is bound consistent (weaker than arc consistent)

hasConsistentLowerBound

protected boolean hasConsistentLowerBound()

tests if the constraint is consistent with respect to the current state of domains

Returns:

true iff the constraint is bound consistent (weaker than arc consistent)

hasConsistentUpperBound

protected boolean hasConsistentUpperBound()

opposite

public AbstractConstraint opposite()

Description copied from interface: Constraint

computes the constraint modelling the counter-opposite condition of this

Specified by:

opposite in interface Constraint

Overrides:

opposite in class AbstractConstraint

Returns:

a new constraint (modelling the opposite condition)

isEquivalentTo

public boolean isEquivalentTo(Constraint compareTo)

Description copied from interface: Constraint

tests the equivalence (logical equality of the conditions) between two constraints. In particular whenever c1.equals(c2), then c1.isEquivalent(c2).

Specified by:

isEquivalentTo in interface Constraint

Overrides:

isEquivalentTo in class AbstractConstraint

Parameters:

compareTo - the constraint to be compared to

Returns:

true if and only if the constraints model the same logical condition.

pretty

public java.lang.String pretty()

Description copied from interface: Entity

pretty printing of the object. This String is not constant and may depend on the context.

Specified by:

pretty in interface Entity

Overrides:

pretty in class AbstractEntity

Returns:

a readable string representation of the object