Hi,
I am running VF2 in igraph (with python interface) and it seems that the algorithm in igraph does not properly support isomorphism with multiple edges between the same two vertices.
Example:
import igraph
Q = igraph.Graph(directed=True)
Q.add_vertices(2)
Q.add_edges([(0,1)])
G = igraph.Graph(directed=True)
G.add_vertices(2)
G.add_edges([(0,1), (0,1)])
print G.get_subisomorphisms_vf2(Q, edge_color1=[1,2], edge_color2=[1]) # empty
print G.get_subisomorphisms_vf2(Q, edge_color1=[2,1], edge_color2=[1]) # one mapping
Is this a known issue? I have seen a few comments around suggesting to use the multiplicity of edges as labels to include in the match, but based on the above example, this still seems problematic unless I am misinterpreting something. Are there any ongoing plans for vf2 to support multiple edges between the same two nodes?
Thanks,
Steve