This post summarizes the PATCHY-SAN algorithm proposed by Niepert et al in their ICML 2016 paper " Learning Convolutional Neural Networks for Graphs " In the literature, the convolution operation on graphs is defined in 3 domains: spectral domain [ Defferrard et al , Kipf et al ], spatial domain [ Masci et al , Boscaini et al ] and embedding domain [ Maron et al ]. The method proposed by Niepert et al in "Learning Convolutional Neural Networks for Graphs" falls into the category of spatial domain algorithm. The broad aim of the paper is to learn a function over a bunch of graphs that will give us a general representation of them. These representations can then be used for any task such graph classification. Challenges in applying convolution directly on graphs: There are two main problems that needs to be addressed before we could apply convolution on graphs. Challenge 1 : Images can be thought of as a regular graph, where each pixel is denoted by a...