net.sf.cpsolver.coursett.constraint
Class GroupConstraint

java.lang.Object
  net.sf.cpsolver.ifs.model.Constraint
      net.sf.cpsolver.coursett.constraint.GroupConstraint

public class GroupConstraint
extends Constraint

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 1.1 (University Course Timetabling)
Copyright (C) 2006 Tomáš Müller
muller@unitime.org
Lazenska 391, 76314 Zlin, Czech Republic

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 2.1 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, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

Field Summary

static String	TYPE_BTB Back-to-back constraint: given classes have to be taught in the same room and they have to follow one strictly after another.
static String	TYPE_BTB_DAY
static String	TYPE_BTB_TIME Back-to-back constraint: given classes have to follow one strictly after another, but they can be taught in different rooms.
static String	TYPE_CAN_SHARE_ROOM
static String	TYPE_CH_NOTOVERLAP
static String	TYPE_DIFF_TIME Different time: given classes cannot overlap in time.
static String	TYPE_EVERY_OTHER_DAY
static String	TYPE_FOLLOWING_DAY
static String	TYPE_MEET_WITH
static String	TYPE_NDB_GT_1
static String	TYPE_NHB_1 One hour between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_NHB_1_5 One and half hour between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_NHB_2 Two hours between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_NHB_3 Three hours between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_NHB_4 Four hours between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_NHB_4_5 Four and half hours between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_NHB_5 Five hours between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_NHB_6 Six hours between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_NHB_7 Seven hours between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_NHB_8 Eight hours between: between the given classes, the exact number of hours have to be kept.
static String	TYPE_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.
static String	TYPE_NHB_LT_6 Less than 6 hours between: between the given classes, the number of hours have to be less than six.
static String	TYPE_PRECEDENCE
static String	TYPE_SAME_DAYS Same days: given classes have to be taught in the same day.
static String	TYPE_SAME_INSTR
static String	TYPE_SAME_ROOM Same room: given classes have to placed in the same room.
static String	TYPE_SAME_START Same room: given classes have to placed in the same room.
static String	TYPE_SAME_STUDENTS
static String	TYPE_SAME_TIME Same time: given classes have to be taught in the same hours.

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

iAssignedVariables, iConstraintListeners

Constructor Summary

GroupConstraint()

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

Method Summary

void	addVariable(Variable variable) Add a variable to this constraint
void	assigned(long iteration, Value value) Given value is to be assigned to its varable.
static boolean	canShareRooms(String type)
void	computeConflicts(Value value, Set conflicts) The only method which has to be implemented by any constraint.
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 (if given placement is assigned)
long	getId() Unique id
String	getName() Constraint's name -- for printing purposes
static String	getName(String type)
int	getPreference() Constraint preference (0 if prohibited or reqired)
String	getPrologPreference() Prolog reference: "R" for required, "P" for prohibited", "-2",.."2" for preference
String	getType() ConstraString type (e.g, TYPE_SAME_TIME
boolean	inConflict(Value 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(Value value1, Value 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()
void	removeVariable(Variable variable) Remove a variable from this constraint
void	setType(String type)
String	toString()
void	unassigned(long iteration, Value value) Given value is unassigned from its varable.

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

addConstraintListener, assignedVariables, constraintListeners, countAssignedVariables, countVariables, equals, getDescription, getModel, hashCode, removeConstraintListener, setModel, variables

Methods inherited from class java.lang.Object

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

Field Detail

TYPE_SAME_TIME

public static String TYPE_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.

TYPE_SAME_DAYS

public static String TYPE_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.

TYPE_BTB

public static String TYPE_BTB

Back-to-back constraint: given classes have to be taught in the same room and they have to follow one strictly after another.

TYPE_BTB_TIME

public static String TYPE_BTB_TIME

Back-to-back constraint: given classes have to follow one strictly after another, but they can be taught in different rooms.

TYPE_DIFF_TIME

public static String TYPE_DIFF_TIME

Different time: given classes cannot overlap in time.

TYPE_NHB_1

public static String TYPE_NHB_1

One hour between: between the given classes, the exact number of hours have to be kept.

TYPE_NHB_2

public static String TYPE_NHB_2

Two hours between: between the given classes, the exact number of hours have to be kept.

TYPE_NHB_3

public static String TYPE_NHB_3

Three hours between: between the given classes, the exact number of hours have to be kept.

TYPE_NHB_4

public static String TYPE_NHB_4

Four hours between: between the given classes, the exact number of hours have to be kept.

TYPE_NHB_5

public static String TYPE_NHB_5

Five hours between: between the given classes, the exact number of hours have to be kept.

TYPE_NHB_6

public static String TYPE_NHB_6

Six hours between: between the given classes, the exact number of hours have to be kept.

TYPE_NHB_7

public static String TYPE_NHB_7

Seven hours between: between the given classes, the exact number of hours have to be kept.

TYPE_NHB_8

public static String TYPE_NHB_8

Eight hours between: between the given classes, the exact number of hours have to be kept.

TYPE_SAME_START

public static String TYPE_SAME_START

Same room: given classes have to placed in the same room.

TYPE_SAME_ROOM

public static String TYPE_SAME_ROOM

Same room: given classes have to placed in the same room.

TYPE_NHB_GTE_1

public static String TYPE_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.

TYPE_NHB_LT_6

public static String TYPE_NHB_LT_6

Less than 6 hours between: between the given classes, the number of hours have to be less than six.

TYPE_NHB_1_5

public static String TYPE_NHB_1_5

One and half hour between: between the given classes, the exact number of hours have to be kept.

TYPE_NHB_4_5

public static String TYPE_NHB_4_5

Four and half hours between: between the given classes, the exact number of hours have to be kept.

TYPE_SAME_STUDENTS

public static String TYPE_SAME_STUDENTS

TYPE_SAME_INSTR

public static String TYPE_SAME_INSTR

TYPE_CAN_SHARE_ROOM

public static String TYPE_CAN_SHARE_ROOM

TYPE_PRECEDENCE

public static String TYPE_PRECEDENCE

TYPE_BTB_DAY

public static String TYPE_BTB_DAY

TYPE_MEET_WITH

public static String TYPE_MEET_WITH

TYPE_NDB_GT_1

public static String TYPE_NDB_GT_1

TYPE_CH_NOTOVERLAP

public static String TYPE_CH_NOTOVERLAP

TYPE_FOLLOWING_DAY

public static String TYPE_FOLLOWING_DAY

TYPE_EVERY_OTHER_DAY

public static String TYPE_EVERY_OTHER_DAY

Constructor Detail

GroupConstraint

public GroupConstraint()

GroupConstraint

public GroupConstraint(Long id,
                       String type,
                       String preference)

Constructor

Parameters:

id - constraint id

type - constraString type (e.g, "SAME_TIME")

preference - time preferent ("R" for required, "P" for prohibited, "-2", "-1", "1", "2" for soft preference)

Method Detail

addVariable

public void addVariable(Variable variable)

Description copied from class: Constraint

Add a variable to this constraint

Overrides:

addVariable in class Constraint

removeVariable

public void removeVariable(Variable variable)

Description copied from class: Constraint

Remove a variable from this constraint

Overrides:

removeVariable in class Constraint

getConstraintId

public Long getConstraintId()

Constraint id

getId

public long getId()

Description copied from class: Constraint

Unique id

Overrides:

getId in class Constraint

getType

public String getType()

ConstraString type (e.g, TYPE_SAME_TIME

setType

public void setType(String 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(Value value1,
                            Value 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

computeConflicts

public void computeConflicts(Value value,
                             Set 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

Parameters:

value - value to be assigned to its varaible

conflicts - resultant set of conflicting values

inConflict

public boolean inConflict(Value 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

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 (if given placement is assigned)

unassigned

public void unassigned(long iteration,
                       Value value)

Description copied from class: Constraint

Given value is unassigned from its varable.

Overrides:

unassigned in class Constraint

assigned

public void assigned(long iteration,
                     Value 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

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

getName

public String getName()

Description copied from class: Constraint

Constraint's name -- for printing purposes

Overrides:

getName in class Constraint

getName

public static String getName(String type)

canShareRooms

public static boolean canShareRooms(String type)

isSatisfied

public boolean isSatisfied()

isChildrenNotOverlap

public boolean isChildrenNotOverlap(Lecture lec1,
                                    Placement plc1,
                                    Lecture lec2,
                                    Placement plc2)