Coreness (JGraphT : a free Java graph library)

java.lang.Object
- org.jgrapht.alg.scoring.Coreness<V,E>

Type Parameters:

V - the graph vertex type

E - the graph edge type

All Implemented Interfaces:

VertexScoringAlgorithm<V,Integer>
```
public class Coreness<V,E>
extends Object
implements VertexScoringAlgorithm<V,Integer>
```
Computes the coreness of each vertex in an undirected graph.
A $k$-core of a graph $G$ is a maximal connected subgraph of $G$ in which all vertices have degree at least $k$. Equivalently, it is one of the connected components of the subgraph of $G$ formed by repeatedly deleting all vertices of degree less than $k$. A vertex $u$ has coreness $c$ if it belongs to a $c$-core but not to any $(c+1)$-core.
If a non-empty k-core exists, then, clearly, $G$ has degeneracy at least $k$, and the degeneracy of $G$ is the largest $k$ for which $G$ has a $k$-core.
As described in the following paper
- D. W. Matula and L. L. Beck. Smallest-last ordering and clustering and graph coloring algorithms. Journal of the ACM, 30(3):417--427, 1983.
it is possible to find a vertex ordering of a finite graph $G$ that optimizes the coloring number of the ordering, in linear time, by using a bucket queue to repeatedly find and remove the vertex of smallest degree.
Author:

Dimitrios Michail

Constructor Summary

Constructors
Constructor Description

Coreness(Graph<V,E> g)
Constructor

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`int`	`getDegeneracy()`	Compute the degeneracy of a graph.
`Map<V,Integer>`	`getScores()`	Get a map with the scores of all vertices
`Integer`	`getVertexScore(V v)`	Get a vertex score

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Coreness
```
public Coreness(Graph<V,E> g)
```
    Constructor
    
    Parameters:
    
    g - the input graph
- Method Detail
  - getScores
```
public Map<V,Integer> getScores()
```
    Get a map with the scores of all vertices
    
    Specified by:
    
    getScores in interface VertexScoringAlgorithm<V,E>
    
    Returns:
    
    a map with all scores
  - getVertexScore
```
public Integer getVertexScore(V v)
```
    Get a vertex score
    
    Specified by:
    
    getVertexScore in interface VertexScoringAlgorithm<V,E>
    
    Parameters:
    
    v - the vertex
    
    Returns:
    
    the score
  - getDegeneracy
```
public int getDegeneracy()
```
    Compute the degeneracy of a graph.
    The degeneracy of a graph is the smallest value of $k$ for which it is $k$-degenerate. In graph theory, a $k$-degenerate graph is an undirected graph in which every subgraph has a vertex of degree at most $k$: that is, some vertex in the subgraph touches $k$ or fewer of the subgraph's edges.
    
    Returns:
    
    the degeneracy of a graph