Package org.ddolib.examples.pigmentscheduling

Class PSRanking

java.lang.Object

org.ddolib.examples.pigmentscheduling.PSRanking

All Implemented Interfaces:

Comparator<PSState>, StateRanking<PSState>

public class PSRanking
extends Object
implements StateRanking<PSState>

Provides a ranking heuristic for comparing two PSState objects within the Production Scheduling Problem (PSP) search framework.

The PSRanking class implements the StateRanking interface and defines a simple heuristic ordering between states based on their total remaining demand. This ranking is typically used by search algorithms such as DDO (Decision Diagram Optimization) to prioritize which states should be expanded first during the exploration of the search tree.

In this implementation, states with a smaller total demand are considered "better" (i.e., ranked higher), as they represent configurations that are closer to satisfying all production demands.

Note: this ranking heuristic is a simple and potentially suboptimal choice. More advanced heuristics may consider additional aspects such as stocking cost accumulation, changeover penalties, or temporal feasibility.

See Also:

• PSState
• StateRanking

Constructor Summary

Constructors

Constructor	Description
PSRanking()

Method Summary

Modifier and Type	Method	Description
int	compare(PSState s1, PSState s2)	Compares two PSP states based on their total remaining demand.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Constructor Details

PSRanking

public PSRanking()

Method Details

compare

public int compare(PSState s1,
 PSState s2)

Compares two PSP states based on their total remaining demand.

The state with the smaller sum of previousDemands values (i.e., fewer remaining demands) is considered to have a better rank.

Specified by:

compare in interface Comparator<PSState>

Parameters:

s1 - the first PSState to compare

s2 - the second PSState to compare

Returns:

a negative integer if s1 is better than s2, zero if they are equivalent, or a positive integer otherwise