org.jgrapht.alg.interfaces

## Interface MinimumSTCutAlgorithm<V,E>

• Type Parameters:
V - the graph vertex type
E - the graph edge type
All Known Implementing Classes:
EdmondsKarpMFImpl, GusfieldGomoryHuCutTree, MaximumFlowAlgorithmBase, PushRelabelMFImpl

public interface MinimumSTCutAlgorithm<V,E>
Given a weighted graph G(V,E) (directed or undirected). This class computes a minimum s-t cut. A cut is a partitioning of the vertices into two disjoint sets S, T such that s ∈ S, t ∈ T, and that S ∪ T = V. The capacity of a cut is defined as the sum of the weights of the edges from S to T. In case of a directed graph, only the edges with their tail in S and their head in T are counted. In cased of a undirected graph, all edges with one endpoint in S and one endpoint in T are counted. For a given s and t, this class computes two partitions S and T such that the capacity of the cut is minimized. When each edge has equal weight, by definition this class minimizes the number of edges from S to T. Note: it is not recommended to use this class to calculate the overall minimum cut in a graph by iteratively invoking this class for all source-sink pairs. This is computationally expensive. Instead, use the StoerWagnerMinimumCut implementation.
Author:
Joris Kinable
• ### Method Summary

All Methods
Modifier and Type Method and Description
double calculateMinCut(V source, V sink)
Computes a minimum capacity s-t cut.
double getCutCapacity()
Returns the capacity of the cut obtained after the last invocation of calculateMinCut(Object, Object)
Set<E> getCutEdges()
Returns the set of edges which run from S to T, in the s-t cut obtained after the last invocation of calculateMinCut(Object, Object) In case of a directed graph, only the edges with their tail in S and their head in T are returned.
Set<V> getSinkPartition()
Returns the sink partition T, t ∈ T, of the cut obtained after the last invocation of calculateMinCut(Object, Object)
Set<V> getSourcePartition()
Returns the source partition S, s ∈ S, of the cut obtained after the last invocation of calculateMinCut(Object, Object)
• ### Method Detail

• #### calculateMinCut

double calculateMinCut(V source,
V sink)
Computes a minimum capacity s-t cut.
Parameters:
source - s
sink - t
Returns:
capacity of the cut
• #### getSourcePartition

Set<V> getSourcePartition()
Returns the source partition S, s ∈ S, of the cut obtained after the last invocation of calculateMinCut(Object, Object)
Returns:
source partition S
• #### getSinkPartition

Set<V> getSinkPartition()
Returns the sink partition T, t ∈ T, of the cut obtained after the last invocation of calculateMinCut(Object, Object)
Returns:
source partition T
• #### getCutEdges

Set<E> getCutEdges()
Returns the set of edges which run from S to T, in the s-t cut obtained after the last invocation of calculateMinCut(Object, Object) In case of a directed graph, only the edges with their tail in S and their head in T are returned. In cased of a undirected graph, all edges with one endpoint in S and one endpoint in T are returned.
Returns:
set of edges which run from S to T