org.cpsolver.studentsct.constraint

Class SectionLimit

java.lang.Object

org.cpsolver.ifs.model.Constraint<V,T>

org.cpsolver.ifs.model.GlobalConstraint<Request,Enrollment>

org.cpsolver.studentsct.constraint.SectionLimit

All Implemented Interfaces:

Comparable<Constraint<Request,Enrollment>>

public class SectionLimit
extends GlobalConstraint<Request,Enrollment>

Section limit constraint. This global constraint ensures that a limit of each section is not exceeded. This means that the total sum of weights of course requests (see Request.getWeight()) enrolled into a section is below the section's limit (see Section.getLimit()).

Sections with negative limit are considered unlimited, and therefore completely ignored by this constraint.

This constraint also check section reservations.

Parameters:

Related Solver Parameters

Parameter	Type	Comment
SectionLimit.PreferDummyStudents	Boolean	If true, requests of dummy (last-like) students are preferred to be selected as conflicting.

Version:

StudentSct 1.3 (Student Sectioning)
Copyright (C) 2007 - 2014 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/.

Author:

Tomáš Müller

Field Summary

Fields inherited from class org.cpsolver.ifs.model.Constraint

iConstraintListeners, iId

Constructor Summary

Constructors

Constructor and Description
SectionLimit(DataProperties cfg) Constructor

Method Summary

Modifier and Type	Method and Description
void	computeConflicts(Assignment<Request,Enrollment> assignment, Enrollment enrollment, Set<Enrollment> conflicts) A given enrollment is conflicting, if there is a section which limit (computed by getEnrollmentWeight(Assignment, Section, Request)) exceeds the section limit.
static double	getEnrollmentWeight(Assignment<Request,Enrollment> assignment, Section section, Request request) Enrollment weight of a section if the given request is assigned.
static double	getUnreservedSpace(Assignment<Request,Enrollment> assignment, Section section, Request request) Remaining unreserved space in a section if the given request is assigned.
boolean	inConflict(Assignment<Request,Enrollment> assignment, Enrollment enrollment) A given enrollment is conflicting, if there is a section which limit(computed by getEnrollmentWeight(Assignment, Section, Request)) exceeds the section limit.
String	toString()

Methods inherited from class org.cpsolver.ifs.model.GlobalConstraint

addVariable, assigned, assignedVariables, countAssignedVariables, getName, removeVariable, unassigned, variables

Methods inherited from class org.cpsolver.ifs.model.Constraint

addConstraintListener, compareTo, computeConflictsNoForwardCheck, constraintListeners, countVariables, equals, getDescription, getId, getModel, hashCode, isConsistent, isHard, removeConstraintListener, setModel

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

SectionLimit

public SectionLimit(DataProperties cfg)

Constructor

Parameters:

cfg - solver configuration

Method Detail

getEnrollmentWeight

public static double getEnrollmentWeight(Assignment<Request,Enrollment> assignment,
                                         Section section,
                                         Request request)

Enrollment weight of a section if the given request is assigned. In order to overcome rounding problems with last-like students ( e.g., 5 students are projected to two sections of limit 2 -- each section can have up to 3 of these last-like students), the weight of the request with the highest weight in the section is changed to a small nominal weight.

Parameters:

assignment - current assignment

section - a section that is of concern

request - a request of a student to be assigned containing the given section

Returns:

section's new weight

getUnreservedSpace

public static double getUnreservedSpace(Assignment<Request,Enrollment> assignment,
                                        Section section,
                                        Request request)

Remaining unreserved space in a section if the given request is assigned. In order to overcome rounding problems with last-like students ( e.g., 5 students are projected to two sections of limit 2 -- each section can have up to 3 of these last-like students), the weight of the request with the highest weight in the section is changed to a small nominal weight.

Parameters:

assignment - current assignment

section - a section that is of concern

request - a request of a student to be assigned containing the given section

Returns:

section's new unreserved space

computeConflicts

public void computeConflicts(Assignment<Request,Enrollment> assignment,
                             Enrollment enrollment,
                             Set<Enrollment> conflicts)

A given enrollment is conflicting, if there is a section which limit (computed by getEnrollmentWeight(Assignment, Section, Request)) exceeds the section limit.
For each of such sections, one or more existing enrollments are (randomly) selected as conflicting until the overall weight is under the limit.

Specified by:

computeConflicts in class Constraint<Request,Enrollment>

Parameters:

enrollment - Enrollment that is being considered

conflicts - all computed conflicting requests are added into this set

assignment - current assignment

inConflict

public boolean inConflict(Assignment<Request,Enrollment> assignment,
                          Enrollment enrollment)

A given enrollment is conflicting, if there is a section which limit(computed by getEnrollmentWeight(Assignment, Section, Request)) exceeds the section limit.

Overrides:

inConflict in class Constraint<Request,Enrollment>

Parameters:

enrollment - Enrollment that is being considered

assignment - current assignment

Returns:

true, if there is a section which will exceed its limit when the given enrollment is assigned

toString

public String toString()

Overrides:

toString in class GlobalConstraint<Request,Enrollment>