What are Graph neural networks (GNNs)?

Graph neural networks (GNNs) are connectionist models that capture the dependence of graphs via message passing between the nodes of graphs. They are extensions of the neural network model to capture the information represented as graphs. However, unlike the standard neural nets, GNNs maintain state information to capture the neighbouurhood properties of the nodes. These states of the nodes of a graph can then be used to produce output labels such as a classification of the node or an arbitrary function value computed by the node. The network tries to learn these encodings(hv) for each of the nodes through a mutual sharing of data among the nodes’ neighbours in an iterative manner until convergence.