The reverse task concludes in synthesis, i.e. in finding a chemical formula or formulae of polymers whose properties must fall within the given range. Let poly(ether ketones) be required to be synthesized possessing the glass transition temperature above 493 K and simultaneously with the melting point below 653 K (the latter is important for successful processing). There are no limits on the values of the rest of properties (solubility parameter, density, dielectric constant, refractive index).

The given task will be solved with the help of the program operating with the finest basic fragments. Let us select the number of basic fragments in repeat units, equal to 7. The solution of the given task yields the chemical formulae of poly(ether ketones), shown in Table A-2-1 (450 000 structures were calculated, from which only 24 structures fell within the required range of properties).