org.metacsp.meta.symbolsAndTime

Class MCSData

java.lang.Object

org.metacsp.meta.symbolsAndTime.MCSData

All Implemented Interfaces:

java.lang.Comparable<MCSData>

public class MCSData
extends java.lang.Object
implements java.lang.Comparable<MCSData>

This class serves as a data structure for maintaining the information associated to minimal critical sets (MCSs). An MCS is a set of Activity variables objects such that imposing only one precedence constraint among any two of them results in resolving a (n-ary) conflict, e.g., a resource conflict. The ESTA scheduling algorithm implemented in the works by inferring MCSs and attempting to impose constraints which sequences one Activity in the MCS wrt the others. The fundamental heuristic that makes this method efficient consists in choosing to post constraints such that (1) sequencing the two decisions (i,j) involved in each constraint has "minimal" consequences with respect to the temporal flexibility (FLEX(i,j)) of the underlying temporal network, and (2) the MCS within which the decisions are chosen at each iteration has the highest value of k, which is a function of FLEX(i,j) for all pairs of activities (i,j) in the MCS. More details on this algorithm and heuristic are available in [A. Cesta, A. Oddi and S. F. Smith, "A Constraint-based Method for Project Scheduling with Time Windows. In Journal of Heuristics, volume 8 (1):109-136, 2002] and [P. Laborie, M. Ghallab, "Planning with Sharable Resource Constraints", IJCAI 1995] respectively.

Author:

Planning and Scheduling Team

Field Summary

Fields

Modifier and Type	Field and Description
Activity	mcsActFrom The source Activity with which mcsPcMin is obtained.
Activity	mcsActTo The destination Activity with which mcsPcMin is obtained.
float	mcsK The value of k for the MCS associated to this MCSData object.
float	mcsPcMin The maximum FLEX(i,j) in the MCS associated to this MCSData object.

Constructor Summary

Constructors

Constructor and Description
MCSData(float pcmin, Activity actFrom, Activity actTo, float k) Create a new MCSData object.

Method Summary

Modifier and Type	Method and Description
int	compareTo(MCSData o) Compare this MCSData object with a reference MCSData object.
java.lang.String	toString() Get a String representation of this MCSData object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

mcsK

public float mcsK

The value of k for the MCS associated to this MCSData object.

mcsPcMin

public float mcsPcMin

The maximum FLEX(i,j) in the MCS associated to this MCSData object.

mcsActFrom

public Activity mcsActFrom

The source Activity with which mcsPcMin is obtained.

mcsActTo

public Activity mcsActTo

The destination Activity with which mcsPcMin is obtained.

Constructor Detail

MCSData

public MCSData(float pcmin,
               Activity actFrom,
               Activity actTo,
               float k)

Create a new MCSData object.

Parameters:

pcmin - The lowest FLEX(i,j) in the MCS associated to this MCSData object.

actFrom - The i-th Activity.

actTo - The j-th Activity.

k - The value of k of the MCS associated to this MCSData object.

Method Detail

compareTo

public int compareTo(MCSData o)

Compare this MCSData object with a reference MCSData object.

Specified by:

compareTo in interface java.lang.Comparable<MCSData>

Parameters:

o - The reference MCSData object

Returns:

-1 if the value of k for the MCS associated to this MCSData object is less than that of the MCS associated to the reference MCSData object; 0 if the value of k for the MCS associated to this MCSData object is equal to that of the MCS associated to the reference MCSData object; 1 otherwise.

toString

public java.lang.String toString()

Get a String representation of this MCSData object.

Overrides:

toString in class java.lang.Object

Returns:

A String describing this MCSData object.