Fig. 6From: A survey on graph kernelsDirect product graph. Two labeled graphs G, H and their direct product graph G×H. The vertices of G and H are labeled with ’C’ (gray) and ’O’ (red). In the direct product graph, there is a vertex for all pairs of vertices of G and H with the same label. Two vertices in the direct product graph are adjacent if and only if the associated pairs of vertices are adjacent in G and HBack to article page