Module org.jgrapht.core
Package org.jgrapht.alg.cycle

Class AhujaOrlinSharmaCyclicExchangeLocalAugmentation<V,​E>

  • Type Parameters:
    V - the vertex type the graph
    E - the edge type of the graph
    public class AhujaOrlinSharmaCyclicExchangeLocalAugmentation<V,​E>
extends Object
    Implementation of an algorithm for the local augmentation problem for the cyclic exchange neighborhood, i.e. it finds subset-disjoint negative cycles in a graph, based on Ravindra K. Ahuja, James B. Orlin, Dushyant Sharma, A composite very large-scale neighborhood structure for the capacitated minimum spanning tree problem, Operations Research Letters, Volume 31, Issue 3, 2003, Pages 185-194, ISSN 0167-6377, https://doi.org/10.1016/S0167-6377(02)00236-5. (http://www.sciencedirect.com/science/article/pii/S0167637702002365) A subset-disjoint cycle is a cycle such that no two vertices in the cycle are in the same subset of a given partition of the whole vertex set. This algorithm returns the first or the best found negative subset-disjoint cycle. In the case of the first found cycle, the cycle has minimum number of vertices. It may enumerate all paths up to the length given by the parameter lengthBound, i.e the algorithm runs in exponential time. This algorithm is used to detect valid cyclic exchanges in a cyclic exchange neighborhood for the Capacitated Minomum Spanning Tree problem AhujaOrlinSharmaCapacitatedMinimumSpanningTree
    Since:
    June 7, 2018
    Author:
    Christoph Grüne
    See Also:
    AhujaOrlinSharmaCapacitatedMinimumSpanningTree

    • Constructor Detail

      • AhujaOrlinSharmaCyclicExchangeLocalAugmentation

        public AhujaOrlinSharmaCyclicExchangeLocalAugmentation​(Graph<V,​E> graph,
                                                       int lengthBound,
                                                       Map<V,​Integer> labelMap,
                                                       boolean bestImprovement)
        Constructs an algorithm with given inputs
        Parameters:
        graph - the directed graph on which to find the negative subset disjoint cycle. The vertices of the graph are labeled according to labelMap.
        lengthBound - the (inclusive) upper bound for the length of cycles to detect
        labelMap - the labelMap of the vertices encoding the subsets of vertices
        bestImprovement - contains whether the best or the first improvement is returned: best if true, first if false

    • Method Detail

      • getLocalAugmentationCycle

        public GraphWalk<V,​E> getLocalAugmentationCycle()
        Calculates a valid subset-disjoint negative cycle. If there is no such cycle, it returns an empty GraphWalk instance
        Returns:
        a valid subset-disjoint negative cycle encoded as GraphWalk