Machine learning for molecules holds great potential for efficiently exploring the
vast chemical space and thus streamlining the drug discovery process by facilitating
the design of new therapeutic molecules. Deep generative models have shown
promising results for molecule generation, but the benefits of specific inductive
biases for learning distributions over small graphs are unclear. Our study aims to
investigate the impact of subgraph structures and vocabulary design on distribution
learning, using small drug molecules as a case study. To this end, we introduce
Subcover, a new subgraph-based fragmentation scheme, and evaluate it through
a two-step variational auto-encoder. Our results show that Subcover’s improved
identification of chemically meaningful subgraphs leads to a relative improvement
of the FCD score by 30%, outperforming previous methods. Our findings highlight
the potential of Subcover to enhance the performance and scalability of existing
methods, contributing to the advancement of drug discovery.