As described in previous section, two aggregation methods, i.e. production and summation form, were used for scoring molecules and their influence on training process were examined. Experiments with different aggregation method under different linker length constraints were carried out and their training curves were shown in Figure . When summation score was used, as shown in Figure , during the training of 200 epochs, the curves of average total score were largely fluctuated in all models constrained with linker length, while the curves for production score (as shown in Figure ) behaved much better. In most of cases, the total score increased to around 0.8 in 50 epochs and can be stabilized more or less at the level for the rest of training.