Package org.jacop.constraints
Class LexOrder
- java.lang.Object
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- org.jacop.constraints.DecomposedConstraint<Constraint>
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- org.jacop.constraints.Constraint
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- org.jacop.constraints.LexOrder
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- All Implemented Interfaces:
RemoveLevelLate
,SatisfiedPresent
,UsesQueueVariable
public class LexOrder extends Constraint implements UsesQueueVariable, SatisfiedPresent, RemoveLevelLate
It constructs a LexOrder (lexicographical order) constraint.The algorithm is based on paper
"Propagation algorithms for lexicographic ordering constraints" by Alan M. Frisch, Brahim Hnich, Zeynep Kiziltan, Ian Miguel, and Toby Walsh , Artificial Intelligence 170 (2006) 803-834.
- Version:
- 4.8
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Field Summary
Fields Modifier and Type Field Description private int
alpha
private int
beta
(package private) static boolean
debug
(package private) static java.util.concurrent.atomic.AtomicInteger
idNumber
(package private) SimpleHashSet<java.lang.Integer>
indexQueue
boolean
lexLT
Is Lex enforcing "<" relationship?(package private) int
n
size of the longest vectorboolean
originalLexLT
Is Lex enforcing "<" relationship?(package private) boolean
satisfied
private boolean
satisfiedWhenDefined
private Store
store
(package private) java.util.Map<IntVar,int[]>
varXToIndex
(package private) java.util.Map<IntVar,int[]>
varYToIndex
IntVar[]
x
Two vectors that have to be lexicographically ordered.IntVar[]
y
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Fields inherited from class org.jacop.constraints.Constraint
afcWeight, atomicExecution, consistencyPruningEvents, constraintScope, earlyTerminationOK, increaseWeight, numberId, scope, trace, watchedVariableGrounded
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Fields inherited from class org.jacop.constraints.DecomposedConstraint
queueIndex
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
consistency(Store store)
It is a (most probably incomplete) consistency function which removes the values from variables domains.private boolean
eqSingletons(IntVar x, IntVar y)
protected void
establishGACInit()
private void
forceLE(int i)
private void
forceLT(int i)
int
getDefaultConsistencyPruningEvent()
void
impose(Store store)
It imposes the constraint in a given store.void
queueVariable(int level, Var var)
This is a function called to indicate which variable in a scope of constraint has changed.(package private) void
reestablishGAC(int i)
void
removeLevelLate(int level)
This function is called in case of the backtrack.boolean
satisfied()
It checks if the constraint is satisfied.java.lang.String
toString()
It produces a string representation of a constraint state.void
updateAlpha()
void
updateBeta(int i)
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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
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Methods inherited from class org.jacop.constraints.DecomposedConstraint
auxiliaryVariables, checkInput, checkInput, checkInputForDuplication, checkInputForDuplicationSkipSingletons, checkInputForNullness, checkInputForNullness, checkInputForNullness, derivative, getDubletonsSkipSingletons, imposeDecomposition
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Field Detail
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idNumber
static java.util.concurrent.atomic.AtomicInteger idNumber
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debug
static final boolean debug
- See Also:
- Constant Field Values
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x
public IntVar[] x
Two vectors that have to be lexicographically ordered.
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y
public IntVar[] y
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lexLT
public boolean lexLT
Is Lex enforcing "<" relationship?
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originalLexLT
public boolean originalLexLT
Is Lex enforcing "<" relationship?
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n
int n
size of the longest vector
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satisfied
boolean satisfied
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store
private Store store
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satisfiedWhenDefined
private boolean satisfiedWhenDefined
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alpha
private int alpha
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beta
private int beta
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indexQueue
SimpleHashSet<java.lang.Integer> indexQueue
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varXToIndex
java.util.Map<IntVar,int[]> varXToIndex
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varYToIndex
java.util.Map<IntVar,int[]> varYToIndex
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Constructor Detail
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LexOrder
public LexOrder(IntVar[] x, IntVar[] y)
It creates a lexicographical order for vectors x and y,vectors x and y does not need to be of the same size. boolean lt defines if we require strict order, Lex_{<} (lt = true) or Lex_{=<} (lt = false)
- Parameters:
x
- first vector constrained by LexOrder constraint.y
- second vector constrained by LexOrder constraint.
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Method Detail
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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.
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getDefaultConsistencyPruningEvent
public int getDefaultConsistencyPruningEvent()
- Specified by:
getDefaultConsistencyPruningEvent
in classConstraint
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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.
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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.
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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.
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removeLevelLate
public void removeLevelLate(int level)
Description copied from interface:RemoveLevelLate
This function is called in case of the backtrack. It is called after all timestamps, variables, mutablevariables have reverted to their values *after* removing the level.- Specified by:
removeLevelLate
in interfaceRemoveLevelLate
- Parameters:
level
- the level which is being removed.
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toString
public java.lang.String toString()
Description copied from class:Constraint
It produces a string representation of a constraint state.- Overrides:
toString
in classConstraint
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establishGACInit
protected void establishGACInit()
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reestablishGAC
void reestablishGAC(int i)
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updateAlpha
public void updateAlpha()
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updateBeta
public void updateBeta(int i)
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forceLT
private void forceLT(int i)
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forceLE
private void forceLE(int i)
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