Package org.jacop.constraints
Class ValuePrecede
- java.lang.Object
-
- org.jacop.constraints.DecomposedConstraint<Constraint>
-
- org.jacop.constraints.Constraint
-
- org.jacop.constraints.ValuePrecede
-
- All Implemented Interfaces:
SatisfiedPresent
,Stateful
,UsesQueueVariable
public class ValuePrecede extends Constraint implements UsesQueueVariable, Stateful, SatisfiedPresent
It defines Value Precedence constraint for integers.Value precedence of s over t in an integer sequence x = [x0,..., xn−1] means if there exists j such that xj = t, then there must exist i < j such that xi = s.
The algorithm is based on paper "Global Constraints for Integer and Set Value Precedence" by Y. C. Law, J. H. Lee Principles and Practice of Constraint Programming (CP'2004).
- Version:
- 4.8
-
-
Field Summary
Fields Modifier and Type Field Description private TimeStamp<java.lang.Integer>
alpha
Defines variables alpha, beta, gamma for the algorithmprivate TimeStamp<java.lang.Integer>
beta
private boolean
firstConsistencyCheck
private TimeStamp<java.lang.Integer>
gamma
(package private) static java.util.concurrent.atomic.AtomicInteger
idNumber
private int
n
protected int
s
It specifies values s and t for the constraint.(package private) Store
store
protected int
t
It specifies values s and t for the constraint.private java.util.Map<IntVar,java.lang.Integer>
varMap
private java.util.LinkedHashSet<IntVar>
varQueue
IntVar[]
x
It specifies lists of variables for the constraint.-
Fields inherited from class org.jacop.constraints.Constraint
afcWeight, atomicExecution, consistencyPruningEvents, constraintScope, earlyTerminationOK, increaseWeight, numberId, scope, trace, watchedVariableGrounded
-
Fields inherited from class org.jacop.constraints.DecomposedConstraint
queueIndex
-
-
Constructor Summary
Constructors Constructor Description ValuePrecede(int s, int t, java.util.List<IntVar> x)
It constructs ValuePrecede.ValuePrecede(int s, int t, IntVar[] x)
It constructs ValuePrecede.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description private void
checkGamma(int i)
void
consistency(Store store)
It is a (most probably incomplete) consistency function which removes the values from variables domains.int
getDefaultConsistencyPruningEvent()
void
impose(Store store)
It imposes the constraint in a given store.private void
initialize()
private void
propagate(int i)
void
queueVariable(int level, Var var)
This is a function called to indicate which variable in a scope of constraint has changed.void
removeLevel(int level)
This function is called in case of the backtrack, so a constraint can clear the queue of changed variables which is no longer valid.boolean
satisfied()
It checks if the constraint is satisfied.java.lang.String
toString()
It produces a string representation of a constraint state.private void
updateBeta()
-
Methods inherited from class org.jacop.constraints.Constraint
afc, arguments, cleanAfterFailure, decompose, getConsistencyPruningEvent, getGuideConstraint, getGuideValue, getGuideVariable, grounded, grounded, id, impose, imposeDecomposition, increaseWeight, intArrayToString, long2int, numberArgs, removeConstraint, requiresMonotonicity, setConsistencyPruningEvent, setConstraintScope, setScope, setScope, setScope, setScope, setScope, setWatchedVariableGrounded, supplyGuideFeedback, toInt, toInt, updateAFC, watchedVariableGrounded
-
Methods inherited from class org.jacop.constraints.DecomposedConstraint
auxiliaryVariables, checkInput, checkInput, checkInputForDuplication, checkInputForDuplicationSkipSingletons, checkInputForNullness, checkInputForNullness, checkInputForNullness, derivative, getDubletonsSkipSingletons, imposeDecomposition
-
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
-
Methods inherited from interface org.jacop.api.Stateful
isStateful
-
-
-
-
Field Detail
-
idNumber
static final java.util.concurrent.atomic.AtomicInteger idNumber
-
store
Store store
-
x
public final IntVar[] x
It specifies lists of variables for the constraint.
-
n
private int n
-
s
protected final int s
It specifies values s and t for the constraint.
-
t
protected final int t
It specifies values s and t for the constraint.
-
alpha
private TimeStamp<java.lang.Integer> alpha
Defines variables alpha, beta, gamma for the algorithm
-
beta
private TimeStamp<java.lang.Integer> beta
-
gamma
private TimeStamp<java.lang.Integer> gamma
-
firstConsistencyCheck
private boolean firstConsistencyCheck
-
varQueue
private java.util.LinkedHashSet<IntVar> varQueue
-
varMap
private final java.util.Map<IntVar,java.lang.Integer> varMap
-
-
Constructor Detail
-
ValuePrecede
public ValuePrecede(int s, int t, IntVar[] x)
It constructs ValuePrecede.- Parameters:
s
- value occuring firstt
- value occuring nextx
- list of arguments x's.
-
ValuePrecede
public ValuePrecede(int s, int t, java.util.List<IntVar> x)
It constructs ValuePrecede.- Parameters:
s
- value occuring firstt
- value occuring nextx
- list of arguments x's.
-
-
Method Detail
-
impose
public void impose(Store store)
Description copied from class:Constraint
It imposes the constraint in a given store.- Overrides:
impose
in classConstraint
- Parameters:
store
- the constraint store to which the constraint is imposed to.
-
getDefaultConsistencyPruningEvent
public int getDefaultConsistencyPruningEvent()
- Specified by:
getDefaultConsistencyPruningEvent
in classConstraint
-
consistency
public void consistency(Store store)
Description copied from class:Constraint
It is a (most probably incomplete) consistency function which removes the values from variables domains. Only values which do not have any support in a solution space are removed.- Specified by:
consistency
in classConstraint
- Parameters:
store
- constraint store within which the constraint consistency is being checked.
-
initialize
private void initialize()
-
propagate
private void propagate(int i)
-
updateBeta
private void updateBeta()
-
checkGamma
private void checkGamma(int i)
-
satisfied
public boolean satisfied()
Description copied from interface:SatisfiedPresent
It checks if the constraint is satisfied. It can return false even if constraint is satisfied but not all variables in its scope are grounded. It needs to return true if all variables in its scope are grounded and constraint is satisfied.Implementations of this interface for constraints that are not PrimitiveConstraint may require constraint imposition and consistency check as a requirement to work correctly.
- Specified by:
satisfied
in interfaceSatisfiedPresent
- Returns:
- true if constraint is possible to verify that it is satisfied.
-
queueVariable
public void queueVariable(int level, Var var)
Description copied from class:Constraint
This is a function called to indicate which variable in a scope of constraint has changed. It also indicates a store level at which the change has occurred.- Overrides:
queueVariable
in classConstraint
- Parameters:
level
- the level of the store at which the change has occurred.var
- variable which has changed.
-
removeLevel
public void removeLevel(int level)
Description copied from interface:Stateful
This function is called in case of the backtrack, so a constraint can clear the queue of changed variables which is no longer valid. This function is called *before* all timestamps, variables, mutablevariables have reverted to their previous value.- Specified by:
removeLevel
in interfaceStateful
- Parameters:
level
- the level which is being removed.
-
toString
public java.lang.String toString()
Description copied from class:Constraint
It produces a string representation of a constraint state.- Overrides:
toString
in classConstraint
-
-