org.cpsolver.studentsct.constraint

Class ReservationLimit

java.lang.Object

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

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

org.cpsolver.studentsct.constraint.ReservationLimit

All Implemented Interfaces:

Comparable<Constraint<Request,Enrollment>>

public class ReservationLimit
extends GlobalConstraint<Request,Enrollment>

Reservation limit constraint. This global constraint ensures that a limit of each reservation is not exceeded. This means that the total sum of weights of course requests (see Request.getWeight()) enrolled into a reservation is below the reservation's limit (see Reservation.getLimit()). It also ensures that the desired space is reserved in the enrollment's offering and configuration.

Parameters:

Related Solver Parameters

Parameter	Type	Comment
ReservationLimit.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
ReservationLimit(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 the reservation's remaining available space (computed by Reservation.getReservedAvailableSpace(Assignment, Request)) is below the requests weight Request.getWeight().
static double	getUnreservedSpace(Assignment<Request,Enrollment> assignment, Config config, Request request, boolean hasReservation) Remaining unreserved space in a config if the given request is assigned.
boolean	inConflict(Assignment<Request,Enrollment> assignment, Enrollment enrollment) A given enrollment is conflicting, if the config's enrollment (computed by ConfigLimit.getEnrollmentWeight(Assignment, Config, Request)) exceeds the 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

ReservationLimit

public ReservationLimit(DataProperties cfg)

Constructor

Parameters:

cfg - solver configuration

Method Detail

getUnreservedSpace

public static double getUnreservedSpace(Assignment<Request,Enrollment> assignment,
                                        Config config,
                                        Request request,
                                        boolean hasReservation)

Remaining unreserved space in a config 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

config - a config that is of concern

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

hasReservation - true if the enrollment in question has a reservation (only not matching the given configuration)

Returns:

config's new unreserved space

computeConflicts

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

A given enrollment is conflicting, if the reservation's remaining available space (computed by Reservation.getReservedAvailableSpace(Assignment, Request)) is below the requests weight Request.getWeight().
If the limit is breached, one or more existing enrollments are selected as conflicting until there is enough space in the reservation. Similarly, if the enrollment does not have the reservation, it is checked that there is enough unreserved space in the desired configuration.

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 the config's enrollment (computed by ConfigLimit.getEnrollmentWeight(Assignment, Config, Request)) exceeds the limit.

Overrides:

inConflict in class Constraint<Request,Enrollment>

Parameters:

enrollment - Enrollment that is being considered

assignment - current assignment

Returns:

true, if the enrollment cannot be assigned without exceeding the limit

toString

public String toString()

Overrides:

toString in class GlobalConstraint<Request,Enrollment>