A type of neural network design used for network and graph-based machine learning applications is called a “Graph Convolutional Network,” or GCN. GCN applies convolutional neural network (CNN) concepts to graphs by using convolution operation to aggregate input from neighboring nodes.

Conventional CNNs operate on regular grids; GCNs operate on irregular graph topologies where nodes and edges can have arbitrary connections.
In a graph convolution network (GCN), every node is associated with a feature vector, and the convolution process is applied to these vectors while accounting for the graph’s topology. The convolution process generates a new set of feature vectors that can be used for node classification, graph classification, and link prediction, or they can be fed into the GCN’s following layers.

GCN Applications

GCNs have been used in many different applications, including recommendation systems, social network analysis, bioinformatics, and natural language processing. They have shown effective in representing intricate connections and dependencies in graph data, and they can advance our understanding of complex systems in a variety of domains.

How Graph Convolution Network works?

Graph Convolutional Networks (GCNs) are a specific family of neural networks designed to handle graph-structured input. Graph convolutional neural networks (GCNs) extend conventional convolutional neural networks (CNNs) to graphs by offering convolution operations that combine and modify the attributes of neighboring nodes. This is an explanation of how GCNs work:

• An instance of a graph, comprising an assemblage of nodes and edges, functions as the GCN’s input. Every node is linked to a feature vector; the connections between two nodes are indicated by each edge.
• A graph’s convolution The core function of GCNs is the graph convolution, which collects and transforms the attributes of neighboring nodes. The convolution operation is defined as follows:

a. Compute the node features for each node i in the graph using the node features and edge weights of its neighbors:
h_i = sum_j (w_ij * x_j)
where x_j is the feature vector of node j, w_ij is the weight of the edge between nodes i and j, and h_i is the new feature vector for node i.
b. Transform the aggregated node features using a neural network layer:
h_i' = f(W*h_i)
where W is a weight matrix and f is an activation function.

Multiple convolutional layers:

Depending on the output of the previous layer, each convolution layer that a GCN uses can compute a new set of features. Every node’s feature vector is updated by the final layer’s output.

Pooling and flattening:

After the last convolution layer, the graph representation is frequently pooled or flattened into a fixed-size feature vector so that it can be utilized for ensuing tasks such as node classification or graph classification.

Training:

Supervised learning techniques are frequently used to train GCNs. These methods involve labelling the graph with a set of target values, like graph labels or node labels. Using a loss function, the network is trained to close the difference between the goal values and the predicted values.

Generally speaking, GCNs gather and modify the properties of neighboring nodes in a graph, making graph-structured data suitable for neural network operations.