Future directions
Graph neural networks are a rapidly evolving discipline. We have covered working with static homogeneous graphs on various popular graph tasks so far, which covers many real-world use cases. However, it is likely that some graphs are neither homogeneous nor static, and neither can they be easily reduced to this form. In this section, we will look at our options for dealing with heterogenous and temporal graphs.
Heterogeneous graphs
Heterogeneous graphs [7], also called heterographs, differ from the graphs we have seen so far in that they may contain different kinds of nodes and edges. These different types of nodes and edges might also contain different types of attributes, including possible representations with different dimensions. Popular examples of heterogeneous graphs are citation graphs that contain authors and papers, recommendation graphs that contain users and products, and knowledge graphs that can contain many different types of entities.
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