where 𝜋 denotes a policy, i.e., probabilities of sampling tokens conditioned on observing a token sequence, 𝑆(𝑥) is the Scoring Function whose value is computed based on a generated SMILES sequence, 𝑥, and 𝜎 is a scalar factor. From equation 2, the augmented log likelihood is comprised of the prior log likelihood adjusted by the desirability of a sampled SMILES sequence based on the Scoring Function. The loss is then defined as follows: