• Token Deletion (Fig. ), which removes specific symbols ('tokens') from a SMILES string to generate variations of the original input. We performed three deletion strategies: o Random deletion, whereby tokens are randomly removed from a given string. A similar approach has been explored for bioactivity prediction. o Random deletion with enforced validity, whereby, after randomly removing tokens, only 'chemically valid' SMILES strings are retained. o Random deletion with protection, whereby only certain types of tokens are subjected to deletion.