Experiments in Predicting Biodegradability

Abstract. We present a novel application of inductive logic program-ming (ILP) in the area of quantitative structure-activity relationships (QSARs). The activity we want to predict is the biodegradability of chemical compounds in water. In particular, the target variable is the half-life in water for aerobic aqueous biodegradation. Structural descrip-tions of chemicals in terms of atoms and bonds are derived from the chemicals ’ SMILES encodings. Denition of substructures are used as background knowledge. Predicting biodegradability is essentially a re-gression problem, but we also consider a discretized version of the target variable. We thus employ a number of relational classication and re-gression methods on the relational representation and compare these to propositional methods applied to dierent propositionalisations of the problem. Some expert comments on the induced theories are also given. 1