Neural Networks: An Overview - Neural Networks: Methodology and Applications - page 63

Fig. 1.40. Results of the TREC-90 routing task; black : results obtained by the
above method; grey : results obtained by other methods

present case, the chemist's knowledge is of utmost importance. Classically,
three categories of features are considered, i.e.,

• chemical features such as the molecular weight, the number of carbon

atoms, etc.;

• geometrical features such as the volume of the molecule, its area, etc;

• electrical features such as the electric charges borne by each atom, dipole

moments, etc.

For each property to be predicted, a set of candidate descriptors must be built,
and selection techniques such as described in Chap. 2 must be applied. Because