JTVAE is an unsupervised generative model consisting of an encoder q φ (Z|D) that maps a set of discrete molecules D = {x 1 , . . . , x n } to a continuous latent space Z and a decoder p θ (D|Z) that does the reverse mapping. The parameters of the encoder φ and the decoder θ are updated using the loss function L VAE . Compared to older molecular generative models, the JTVAE achieved the ability to generate almost all meaningful SMILES strings in the limit of its vocabulary set, due to exploiting molecular subgraphs as clusters on junction trees.