Introducing heterogeneous graphs

Heterogeneous graphs are a powerful tool to represent general relationships between different entities. Having different types of nodes and edges creates graph structures that are more complex but also more difficult to learn. In particular, one of the main problems with heterogeneous networks is that features from different types of nodes or edges do not necessarily have the same meaning or dimensionality. Therefore, merging different features would destroy a lot of information. This is not the case with homogeneous graphs, where each dimension has the exact same meaning for every node or edge.

Heterogeneous graphs are a more general kind of network that can represent different types of nodes and edges. Formally, it is defined as a graph, , comprising , a set of nodes, and , a set of edges. In the heterogeneous setting, it is associated with a node-type mapping function, (where denotes the set of node types), and a link-type mapping function,...