org.jgrapht.alg.independentset

Class ChordalGraphIndependentSetFinder<V,E>

java.lang.Object

org.jgrapht.alg.independentset.ChordalGraphIndependentSetFinder<V,E>

Type Parameters:

V - the graph vertex type.

E - the graph edge type.

All Implemented Interfaces:

IndependentSetAlgorithm<V>

public class ChordalGraphIndependentSetFinder<V,E>
extends Object
implements IndependentSetAlgorithm<V>

Calculates a maximum cardinality independent set in a chordal graph. A chordal graph is a simple graph in which all cycles of four or more vertices have a chord. A chord is an edge that is not part of the cycle but connects two vertices of the cycle. To compute the independent set, this implementation relies on the ChordalityInspector to compute a perfect elimination order. The maximum cardinality independent set for a chordal graph is computed in $\mathcal{O}(|V| + |E|)$ time. All the methods in this class are invoked in a lazy fashion, meaning that computations are only started once the method gets invoked.

Author:

Timofey Chudakov

Nested Class Summary

Nested classes/interfaces inherited from interface org.jgrapht.alg.interfaces.IndependentSetAlgorithm

IndependentSetAlgorithm.IndependentSet<V>, IndependentSetAlgorithm.IndependentSetImpl<V>

Constructor Summary

Constructors

Constructor and Description
ChordalGraphIndependentSetFinder(Graph<V,E> graph) Creates a new ChordalGraphIndependentSetFinder instance.
ChordalGraphIndependentSetFinder(Graph<V,E> graph, ChordalityInspector.IterationOrder iterationOrder) Creates a new ChordalGraphIndependentSetFinder instance.

Method Summary

Modifier and Type	Method and Description
IndependentSetAlgorithm.IndependentSet<V>	getIndependentSet() Returns a maximum cardinality independent set of the inspected graph.

Methods inherited from class java.lang.Object

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

Constructor Detail

ChordalGraphIndependentSetFinder

public ChordalGraphIndependentSetFinder(Graph<V,E> graph)

Creates a new ChordalGraphIndependentSetFinder instance. The ChordalityInspector used in this implementation uses the default MaximumCardinalityIterator iterator.

Parameters:

graph - graph

ChordalGraphIndependentSetFinder

public ChordalGraphIndependentSetFinder(Graph<V,E> graph,
                                        ChordalityInspector.IterationOrder iterationOrder)

Creates a new ChordalGraphIndependentSetFinder instance. The ChordalityInspector used in this implementation uses either the MaximumCardinalityIterator iterator or the LexBreadthFirstIterator iterator, depending on the parameter iterationOrder.

Parameters:

graph - graph

iterationOrder - constant which defines iterator to be used by the ChordalityInspector in this implementation.

Method Detail

getIndependentSet

public IndependentSetAlgorithm.IndependentSet<V> getIndependentSet()

Returns a maximum cardinality independent set of the inspected graph. If the graph isn't chordal, returns null.

Specified by:

getIndependentSet in interface IndependentSetAlgorithm<V>

Returns:

a maximum independent set of the graph if it is chordal, null otherwise.