GroupConstraint (Constraint Solver API Documentation -- CPSolver v1.2 build 156)

java.lang.Object
- net.sf.cpsolver.ifs.model.Constraint<Lecture,Placement>
- - net.sf.cpsolver.coursett.constraint.GroupConstraint

All Implemented Interfaces:: Comparable<Constraint<Lecture,Placement>>

public class GroupConstraint
extends Constraint<Lecture,Placement>

Group constraint.
This constraint expresses relations between several classes, e.g., that two sections of the same lecture can not be taught at the same time, or that some classes have to be taught one immediately after another. It can be either hard or soft.

Following constraints are now supported:

Constraint	Comment
SAME_TIME	Same time: given classes have to be taught in the same hours. If the classes are of different length, the smaller one cannot start before the longer one and it cannot end after the longer one.
SAME_DAYS	Same days: given classes have to be taught in the same day. If the classes are of different time patterns, the days of one class have to form a subset of the days of the other class.
BTB	Back-to-back constraint: given classes have to be taught in the same room and they have to follow one strictly after another.
BTB_TIME	Back-to-back constraint: given classes have to follow one strictly after another, but they can be taught in different rooms.
DIFF_TIME	Different time: given classes cannot overlap in time.
NHB(1), NHB(1.5), NHB(2), ... NHB(8)	Number of hours between: between the given classes, the exact number of hours have to be kept.
SAME_START	Same starting hour: given classes have to start in the same hour.
SAME_ROOM	Same room: given classes have to be placed in the same room.
NHB_GTE(1)	Greater than or equal to 1 hour between: between the given classes, the number of hours have to be one or more.
NHB_LT(6)	Less than 6 hours between: between the given classes, the number of hours have to be less than six.

Version:: CourseTT 1.2 (University Course Timetabling)
Copyright (C) 2006 - 2010 Tomáš Müller
muller@unitime.org
http://muller.unitime.org

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not see http://www.gnu.org/licenses/.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`GroupConstraint.ConstraintType` Group constraint type.
`static class`	`GroupConstraint.Flag` Group constraint building blocks (individual constraints that need more than `GroupConstraint.PairCheck`)
`static interface`	`GroupConstraint.PairCheck` Group constraints that can be checked on pairs of classes (e.g., same room means any two classes are in the same room), only need to implement this interface.

Field Summary
- Fields inherited from class net.sf.cpsolver.ifs.model.Constraint
  iAssignedVariables, iConstraintListeners, iId

Constructor Summary

Constructors
Constructor and Description

GroupConstraint()

GroupConstraint(Long id, GroupConstraint.ConstraintType type, String preference)
Constructor

Constructors
Constructor and Description
`GroupConstraint()`
`GroupConstraint(Long id, GroupConstraint.ConstraintType type, String preference)` Constructor

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addVariable(Lecture lecture)` Add a variable to this constraint
`void`	`assigned(long iteration, Placement value)` Given value is to be assigned to its varable.
`boolean`	`canShareRoom()`
`void`	`computeConflicts(Placement value, Set<Placement> conflicts)` The only method which has to be implemented by any constraint.
`boolean`	`equals(Object o)` Compare two constraints for equality (`Constraint.getId()` is used)
`boolean`	`forwardCheck(Placement value, Set<GroupConstraint> ignore, int depth)`
`void`	`forwardCheck(Placement value, Set<Placement> conflicts, Set<GroupConstraint> ignore, int depth)`
`Long`	`getConstraintId()` Constraint id
`int`	`getCurrentPreference()` Current constraint preference (0 if prohibited or reqired, depends on current satisfaction of the constraint)
`int`	`getCurrentPreference(Placement placement)` Current constraint preference change (if given placement is assigned)
`protected long`	`getGeneratedId()` Generated unique id
`long`	`getId()` Unique id
`String`	`getName()` Constraint's name -- for printing purposes
`int`	`getPreference()` Constraint preference (0 if prohibited or reqired)
`String`	`getPrologPreference()` Prolog reference: "R" for required, "P" for prohibited", "-2",.."2" for preference
`GroupConstraint.ConstraintType`	`getType()` ConstraString type (e.g, `GroupConstraint.ConstraintType.SAME_TIME`)
`boolean`	`inConflict(Placement value)` Returns true if the given assignment is inconsistent with the existing assignments respecting this constraint.
`boolean`	`isChildrenNotOverlap(Lecture lec1, Placement plc1, Lecture lec2, Placement plc2)`
`boolean`	`isConsistent(Placement value1, Placement value2)` Returns true if the given assignments are consistent respecting this constraint.
`boolean`	`isHard()` Returns true if the constraint is hard.
`boolean`	`isProhibited()` Is constraint prohibited
`boolean`	`isRequired()` Is constraint required
`boolean`	`isSatisfied()`
`boolean`	`isSatisfiedPair(Placement plc1, Placement plc2)`
`void`	`removeVariable(Lecture lecture)` Remove a variable from this constraint
`void`	`setModel(Model<Lecture,Placement> model)` Sets the model which the constraint belongs to
`void`	`setType(GroupConstraint.ConstraintType type)`
`String`	`toString()`
`void`	`unassigned(long iteration, Placement value)` Given value is unassigned from its variable.

Methods inherited from class net.sf.cpsolver.ifs.model.Constraint
addConstraintListener, assignedVariables, compareTo, constraintListeners, countAssignedVariables, countVariables, getDescription, getModel, hashCode, removeConstraintListener, variables

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - GroupConstraint
```
public GroupConstraint()
```
  - GroupConstraint
```
public GroupConstraint(Long id,
                       GroupConstraint.ConstraintType type,
                       String preference)
```
    Constructor
    
    Parameters:
    
    id - constraint id
    
    type - constraString type (e.g, GroupConstraint.ConstraintType.SAME_TIME)
    
    preference - time preference ("R" for required, "P" for prohibited, "-2", "-1", "1", "2" for soft preference)
- Method Detail
  - setModel
```
public void setModel(Model<Lecture,Placement> model)
```
    Description copied from class: Constraint
    
    Sets the model which the constraint belongs to
    
    Overrides:
    
    setModel in class Constraint<Lecture,Placement>
  - addVariable
```
public void addVariable(Lecture lecture)
```
    Description copied from class: Constraint
    
    Add a variable to this constraint
    
    Overrides:
    
    addVariable in class Constraint<Lecture,Placement>
  - removeVariable
```
public void removeVariable(Lecture lecture)
```
    Description copied from class: Constraint
    
    Remove a variable from this constraint
    
    Overrides:
    
    removeVariable in class Constraint<Lecture,Placement>
  - getConstraintId
```
public Long getConstraintId()
```
    Constraint id
  - getId
```
public long getId()
```
    Description copied from class: Constraint
    
    Unique id
    
    Overrides:
    
    getId in class Constraint<Lecture,Placement>
  - getGeneratedId
```
protected long getGeneratedId()
```
    Generated unique id
  - getType
```
public GroupConstraint.ConstraintType getType()
```
    ConstraString type (e.g, GroupConstraint.ConstraintType.SAME_TIME)
  - setType
```
public void setType(GroupConstraint.ConstraintType type)
```
  - isRequired
```
public boolean isRequired()
```
    Is constraint required
  - isProhibited
```
public boolean isProhibited()
```
    Is constraint prohibited
  - getPrologPreference
```
public String getPrologPreference()
```
    Prolog reference: "R" for required, "P" for prohibited", "-2",.."2" for preference
  - isConsistent
```
public boolean isConsistent(Placement value1,
                            Placement value2)
```
    Description copied from class: Constraint
    
    Returns true if the given assignments are consistent respecting this constraint. This method is used by MAC (see MacPropagation).
    
    Overrides:
    
    isConsistent in class Constraint<Lecture,Placement>
  - computeConflicts
```
public void computeConflicts(Placement value,
                             Set<Placement> conflicts)
```
    Description copied from class: Constraint
    
    The only method which has to be implemented by any constraint. It returns the values which needs to be unassigned in order to make this constraint consistent with the given value if it is assigned to its variable. The computed list of conflicting values is added to the given set of conflicts.
    
    Specified by:
    
    computeConflicts in class Constraint<Lecture,Placement>
    
    Parameters:
    
    value - value to be assigned to its varaible
    
    conflicts - resultant set of conflicting values
  - forwardCheck
```
public void forwardCheck(Placement value,
                         Set<Placement> conflicts,
                         Set<GroupConstraint> ignore,
                         int depth)
```
  - inConflict
```
public boolean inConflict(Placement value)
```
    Description copied from class: Constraint
    
    Returns true if the given assignment is inconsistent with the existing assignments respecting this constraint. This method is used by MAC (see MacPropagation).
    
    Overrides:
    
    inConflict in class Constraint<Lecture,Placement>
  - forwardCheck
```
public boolean forwardCheck(Placement value,
                            Set<GroupConstraint> ignore,
                            int depth)
```
  - getPreference
```
public int getPreference()
```
    Constraint preference (0 if prohibited or reqired)
  - getCurrentPreference
```
public int getCurrentPreference()
```
    Current constraint preference (0 if prohibited or reqired, depends on current satisfaction of the constraint)
  - getCurrentPreference
```
public int getCurrentPreference(Placement placement)
```
    Current constraint preference change (if given placement is assigned)
  - unassigned
```
public void unassigned(long iteration,
                       Placement value)
```
    Description copied from class: Constraint
    
    Given value is unassigned from its variable.
    
    Overrides:
    
    unassigned in class Constraint<Lecture,Placement>
  - assigned
```
public void assigned(long iteration,
                     Placement value)
```
    Description copied from class: Constraint
    
    Given value is to be assigned to its varable. In this method, the constraint should unassigns all varaibles which are in conflict with the given assignment because of this constraint.
    
    Overrides:
    
    assigned in class Constraint<Lecture,Placement>
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - isHard
```
public boolean isHard()
```
    Description copied from class: Constraint
    
    Returns true if the constraint is hard. Only hard constraints are allowed to unassign a variable when there is a conflict with a value that is being assigned
    
    Overrides:
    
    isHard in class Constraint<Lecture,Placement>
  - getName
```
public String getName()
```
    Description copied from class: Constraint
    
    Constraint's name -- for printing purposes
    
    Overrides:
    
    getName in class Constraint<Lecture,Placement>
  - isSatisfied
```
public boolean isSatisfied()
```
  - isChildrenNotOverlap
```
public boolean isChildrenNotOverlap(Lecture lec1,
                                    Placement plc1,
                                    Lecture lec2,
                                    Placement plc2)
```
  - isSatisfiedPair
```
public boolean isSatisfiedPair(Placement plc1,
                               Placement plc2)
```
  - canShareRoom
```
public boolean canShareRoom()
```
  - equals
```
public boolean equals(Object o)
```
    Description copied from class: Constraint
    
    Compare two constraints for equality (Constraint.getId() is used)
    
    Overrides:
    
    equals in class Constraint<Lecture,Placement>

Class GroupConstraint

Nested Class Summary

Field Summary

Fields inherited from class net.sf.cpsolver.ifs.model.Constraint

Constructor Summary

Method Summary

Methods inherited from class net.sf.cpsolver.ifs.model.Constraint

Methods inherited from class java.lang.Object

Constructor Detail

GroupConstraint

GroupConstraint

Method Detail

setModel

addVariable

removeVariable

getConstraintId

getId

getGeneratedId

getType

setType

isRequired

isProhibited

getPrologPreference

isConsistent

computeConflicts

forwardCheck

inConflict

forwardCheck

getPreference

getCurrentPreference

getCurrentPreference

unassigned

assigned

toString

isHard

getName

isSatisfied

isChildrenNotOverlap

isSatisfiedPair

canShareRoom

equals