The development of the lazar system was more or less a byproduct of editing this book. The intention was to demonstrate how to use some of the concepts from previous chapters as building blocks for the creation of a simple predictive toxicology system that can serve as a reference for further developments. Most of the machine learning and data mining techniques have been described in an earlier chapter (1). Some of the basic ideas (utilizing linear fragments for predictions) were developed already in the 1980s by Klopman and

are implemented in the MC4PC system. [a description of MC4PC is given elsewhere in this book (2)]. Please note that lazar is not a reimplementation of an existing system, because it uses its own distinct algorithms to generate descriptors and to achieve the predictions.