contains a partial list of compound characteristics which typically are used by chemists to select synthons along with brief comments regarding the application of each characteristic for example if a combinatorial library of lipophilic compounds is desired synthons which are lipophilic will be selected methods for calculating lipophilicity are described in the martin et al article incorporated by reference hereinabove these and other rules regarding the types of synthons to select in order to obtain given characteristics in the target library are incorporated into the knowledge base of the present invention those skilled in the relevant art will appreciate that many different rules can be incorporated into the knowledge base and the scope of the present invention is not limited to a knowledge base containing any one or more rules table 1______________________________________lipophilicity in general a desirable range for the lipophilicity of finished compounds is between 0 and 5 hydrogen bonding ability measured by the number of heteroatoms molecular weight the molecular weight of the most preferred finished compounds is less than 700 diversity of atom descriptors a library of finished compounds should not be concentrated in a particular class along any of the commonly used atom pair or atom torsion descriptors but rather should make up a diverse set polyaromatics are generally undesirable in a library of finished compounds because they are considered to be cancer causing agents anilines are generally undesirable.