Similarity propagation resembles diffusion of a graph. A: Propagation graph from Figure 2, redrawn with labels for element pairs (diamonds). B: Similarity propagation on a pair propagation graph. Nodes in the graph correspond to element pairs in the original networks. Edges indicate that information can be propagated simultaneously for both elements in a pair. For instance, similarity information can be propagated from the pair (a,p) to the pair (x,y), resulting in the edge 1 → 9 with a weight α · α. C: Feature propagation entails a similar process with more paths for propagation. For instance, similarity information could now be propagated from the pair (a,y) to the pair (x,y), resulting in the edge 5 → 9 with weight α · 1.