net.sf.cpsolver.coursett.constraint
Class JenrlConstraint

java.lang.Object
  extended by net.sf.cpsolver.ifs.model.Constraint<V,T>
      extended by net.sf.cpsolver.ifs.model.BinaryConstraint<Lecture,Placement>
          extended by net.sf.cpsolver.coursett.constraint.JenrlConstraint
All Implemented Interfaces:
Comparable<Constraint<Lecture,Placement>>, WeakeningConstraint<Lecture,Placement>

public class JenrlConstraint
extends BinaryConstraint<Lecture,Placement>
implements WeakeningConstraint<Lecture,Placement>

Join student enrollment constraint.
This constraint is placed between all pairs of classes where there is at least one student attending both classes. It represents a number of student conflicts (number of joined enrollments), if the given two classes overlap in time.
Also, it dynamically maintains the counter of all student conflicts. It is a soft constraint.

Version:
CourseTT 1.2 (University Course Timetabling)
Copyright (C) 2006 - 2010 Tomas Muller
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/.

Field Summary
 
Fields inherited from class net.sf.cpsolver.ifs.model.Constraint
iAssignedVariables, iConstraintListeners, iId
 
Constructor Summary
JenrlConstraint()
          Constructor
 
Method Summary
 void addVariable(Lecture variable)
          Add a variable to this constraint
 boolean areStudentConflictsCommitted()
           
 boolean areStudentConflictsDistance()
           
 boolean areStudentConflictsDistance(Placement value)
           
 boolean areStudentConflictsHard()
           
 void assigned(long iteration, Placement value)
          Given value is to be assigned to its varable.
 void computeConflicts(Placement value, Set<Placement> conflicts)
          The only method which has to be implemented by any constraint.
 void decJenrl(Student student)
          Decrement the number of joined enrollments (during student final sectioning)
 Set<Student> getInstructors()
           
 long getJenrl()
          Number of joined enrollments (during student final sectioning)
 double getJenrlWeight(Student student)
           
 String getName()
          Constraint's name -- for printing purposes
 int getNrInstructors()
           
 int getNrStudents()
           
 Set<Student> getStudents()
           
 void incJenrl(Student student)
          Increment the number of joined enrollments (during student final sectioning)
 boolean inConflict(Placement value)
          Returns true if the given assignment is inconsistent with the existing assignments respecting this constraint.
 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 isInConflict()
          True if the given two lectures overlap in time
static boolean isInConflict(Placement p1, Placement p2, DistanceMetric m)
          Returns true if the given placements are overlapping or they are back-to-back and too far for students.
 boolean isOfTheSameProblem()
           
 boolean isOverLimit()
           
 boolean isToBeIgnored()
          Returns true if there is IgnoreStudentConflictsConstraint between the two lectures.
 double jenrl()
           
 long jenrl(Lecture variable, Placement value)
          Number of joined enrollments if the given value is assigned to the given variable
 double priority()
           
 String toString()
           
 void unassigned(long iteration, Placement value)
          Given value is unassigned from its variable.
 void weaken()
          Weaken the constraint.
 void weaken(Placement value)
          Weaken the constraint enough so that it can assign the given value.
 
Methods inherited from class net.sf.cpsolver.ifs.model.BinaryConstraint
another, first, isFirst, second
 
Methods inherited from class net.sf.cpsolver.ifs.model.Constraint
addConstraintListener, assignedVariables, compareTo, constraintListeners, countAssignedVariables, countVariables, equals, getDescription, getId, getModel, hashCode, removeConstraintListener, removeVariable, setModel, variables
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

JenrlConstraint

public JenrlConstraint()
Constructor

Method Detail

addVariable

public void addVariable(Lecture variable)
Description copied from class: Constraint
Add a variable to this constraint

Overrides:
addVariable in class BinaryConstraint<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

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>

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>

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>

isInConflict

public static boolean isInConflict(Placement p1,
                                   Placement p2,
                                   DistanceMetric m)
Returns true if the given placements are overlapping or they are back-to-back and too far for students.


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>

jenrl

public long jenrl(Lecture variable,
                  Placement value)
Number of joined enrollments if the given value is assigned to the given variable


isInConflict

public boolean isInConflict()
True if the given two lectures overlap in time


incJenrl

public void incJenrl(Student student)
Increment the number of joined enrollments (during student final sectioning)


getJenrlWeight

public double getJenrlWeight(Student student)

decJenrl

public void decJenrl(Student student)
Decrement the number of joined enrollments (during student final sectioning)


getJenrl

public long getJenrl()
Number of joined enrollments (during student final sectioning)


jenrl

public double jenrl()

priority

public double priority()

getNrStudents

public int getNrStudents()

getStudents

public Set<Student> getStudents()

getNrInstructors

public int getNrInstructors()

getInstructors

public Set<Student> getInstructors()

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>

isOverLimit

public boolean isOverLimit()

getName

public String getName()
Description copied from class: Constraint
Constraint's name -- for printing purposes

Overrides:
getName in class Constraint<Lecture,Placement>

toString

public String toString()
Overrides:
toString in class Object

areStudentConflictsHard

public boolean areStudentConflictsHard()

areStudentConflictsDistance

public boolean areStudentConflictsDistance()

areStudentConflictsCommitted

public boolean areStudentConflictsCommitted()

areStudentConflictsDistance

public boolean areStudentConflictsDistance(Placement value)

isOfTheSameProblem

public boolean isOfTheSameProblem()

weaken

public void weaken()
Description copied from interface: WeakeningConstraint
Weaken the constraint. This method is called if the constraint participates in an unassigned of a variable.

Specified by:
weaken in interface WeakeningConstraint<Lecture,Placement>

weaken

public void weaken(Placement value)
Description copied from interface: WeakeningConstraint
Weaken the constraint enough so that it can assign the given value.

Specified by:
weaken in interface WeakeningConstraint<Lecture,Placement>

isToBeIgnored

public boolean isToBeIgnored()
Returns true if there is IgnoreStudentConflictsConstraint between the two lectures.



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