FTrees-FS is the combinatorial fragment space extension module to FTrees, our fast similarity-based search engine.

The underlying concept is strikingly easy: instead of searching already "assembled" molecules, FTrees instead performs a combinatorial build-up of compounds from "fragments". Sources of fragments can be either combinatorial libraries or any fragment-generating procedure.

With FTrees-FS you can perform the fragment assembling steps and at the same time make use of the search/comparison/screening facilities on the level of Feature Tree similarity. Recent applications have demonstrated searches in spaces large as 10¹⁷.