Applications
As subgraph isomorphism has been applied in the area of cheminformatics to find similarities between chemical compounds from their structural formula; often in this area the term substructure search is used. Typically a query structure is defined as SMARTS, a SMILES extension.
The closely related problem of counting the number of isomorphic copies of a graph H in a larger graph G has been applied to pattern discovery in databases, the bioinformatics of protein-protein interaction networks, and in exponential random graph methods for mathematically modeling social networks.
Ohlrich et al. (1993) describe an application of subgraph isomorphism in the computer-aided design of electronic circuits. Subgraph matching is also a substep in graph rewriting (the most runtime-intensive), and thus offered by graph rewrite tools.
Read more about this topic: Subgraph Isomorphism Problem