Package org.ddolib.examples.tsp

Class TSPRelax

java.lang.Object

org.ddolib.examples.tsp.TSPRelax

All Implemented Interfaces:

Relaxation<TSPState>

public class TSPRelax
extends Object
implements Relaxation<TSPState>

Implementation of a relaxation for the Traveling Salesman Problem (TSP).

This class implements the Relaxation interface for TSPState. It provides methods to merge multiple states into a single relaxed state and to adjust the cost of transitions in a relaxed context.

In this implementation:

• mergeStates(Iterator) returns a state where the "toVisit" and "current" sets are the union of the corresponding sets from the input states.
• relaxEdge(TSPState, TSPState, TSPState, Decision, double) currently returns the original cost without modification.

See Also:

• TSPState
• Relaxation

Constructor Summary

Constructors

Constructor	Description
TSPRelax(TSPProblem problem)	Constructs a relaxation for a given TSP problem.

Method Summary

Modifier and Type	Method	Description
TSPState	mergeStates(Iterator<TSPState> states)	Merges multiple TSPState instances into a single relaxed state.
double	relaxEdge(TSPState from, TSPState to, TSPState merged, Decision d, double cost)	Relaxes the cost of a transition between states.

Methods inherited from class java.lang.Object

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

Constructor Details

TSPRelax

public TSPRelax(TSPProblem problem)

Constructs a relaxation for a given TSP problem.

Parameters:

problem - the TSP problem instance to be relaxed

Method Details

mergeStates

public TSPState mergeStates(Iterator<TSPState> states)

Merges multiple TSPState instances into a single relaxed state.

The resulting state has its "toVisit" and "current" sets as the union of the corresponding sets from all input states.

Specified by:

mergeStates in interface Relaxation<TSPState>

Parameters:

states - an iterator over the states to merge

Returns:

a new TSPState representing the merged state

relaxEdge

public double relaxEdge(TSPState from,
 TSPState to,
 TSPState merged,
 Decision d,
 double cost)

Relaxes the cost of a transition between states.

In this implementation, the cost is not modified and the original cost is returned.

Specified by:

relaxEdge in interface Relaxation<TSPState>

Parameters:

from - the state before the transition

to - the state after the transition

merged - the merged state (if any)

d - the decision causing the transition

cost - the original cost of the transition

Returns:

the relaxed cost of the transition (same as the original cost)