/**
* Compute the unique decomposition of the input graph G (atoms of G). Implementation of algorithm
* Atoms as described in Berry et al. (2010), DOI:10.3390/a3020197, <a
* href="http://www.mdpi.com/1999-4893/3/2/197">http://www.mdpi.com/1999-4893/3/2/197</a>
*/
private void computeAtoms() {
if (chordalGraph == null) {
computeMinimalTriangulation();
}
separators = new HashSet<>();
// initialize g' as subgraph of graph (same vertices and edges)
UndirectedGraph<V, E> gprime = copyAsSimpleGraph(graph);
// initialize h' as subgraph of chordalGraph (same vertices and edges)
UndirectedGraph<V, E> hprime = copyAsSimpleGraph(chordalGraph);
atoms = new HashSet<>();
Iterator<V> iterator = meo.descendingIterator();
while (iterator.hasNext()) {
V v = iterator.next();
if (generators.contains(v)) {
Set<V> separator = new HashSet<>(Graphs.neighborListOf(hprime, v));
if (isClique(graph, separator)) {
if (separator.size() > 0) {
if (separators.contains(separator)) {
fullComponentCount.put(separator, fullComponentCount.get(separator) + 1);
} else {
fullComponentCount.put(separator, 2);
separators.add(separator);
}
}
UndirectedGraph<V, E> tmpGraph = copyAsSimpleGraph(gprime);
tmpGraph.removeAllVertices(separator);
ConnectivityInspector<V, E> con = new ConnectivityInspector<>(tmpGraph);
if (con.isGraphConnected()) {
throw new RuntimeException("separator did not separate the graph");
}
for (Set<V> component : con.connectedSets()) {
if (component.contains(v)) {
gprime.removeAllVertices(component);
component.addAll(separator);
atoms.add(new HashSet<>(component));
assert (component.size() > 0);
break;
}
}
}
}
hprime.removeVertex(v);
}
if (gprime.vertexSet().size() > 0) {
atoms.add(new HashSet<>(gprime.vertexSet()));
}
}
/** . */
public void testDirectedGraph() {
ListenableDirectedGraph<String, DefaultEdge> g =
new ListenableDirectedGraph<String, DefaultEdge>(DefaultEdge.class);
g.addVertex(V1);
g.addVertex(V2);
g.addVertex(V3);
g.addEdge(V1, V2);
ConnectivityInspector<String, DefaultEdge> inspector =
new ConnectivityInspector<String, DefaultEdge>(g);
g.addGraphListener(inspector);
assertEquals(false, inspector.isGraphConnected());
g.addEdge(V1, V3);
assertEquals(true, inspector.isGraphConnected());
}
/** . */
public void testIsGraphConnected() {
Pseudograph<String, DefaultEdge> g = create();
ConnectivityInspector<String, DefaultEdge> inspector =
new ConnectivityInspector<String, DefaultEdge>(g);
assertEquals(false, inspector.isGraphConnected());
g.removeVertex(V4);
inspector = new ConnectivityInspector<String, DefaultEdge>(g);
assertEquals(true, inspector.isGraphConnected());
g.removeVertex(V1);
assertEquals(1, g.edgeSet().size());
g.removeEdge(e2);
g.addEdge(V2, V2);
assertEquals(1, g.edgeSet().size());
inspector = new ConnectivityInspector<String, DefaultEdge>(g);
assertEquals(false, inspector.isGraphConnected());
}
