Similarity search is becoming popular in even more disciplines, such as multimedia databases, bioinformatics, data mining, or social networks. The large-scale search engines for such data are mostly based on models involving low-level features and simple similarity functions. There also exist complex models employing local features and higher-level similarities which provide higher retrieval effectiveness. An application of complex models, however, is not feasible at large scale due to insufficient portfolio of indexing techniques enabling fast search.

Many areas of chemical biology, e.g. drug discovery, largely rely on libraries of molecules for production processes. Since the space of all molecules, called the chemical space, is huge, those libraries contain only small subspace of the whole space. An alternative to statical libraries is dynamic exploration of the space. The exploration generates molecules dynamically based on paths between given molecules in the chemical space.