In summary, the incorporation of methodologies such as based-reaction, multi-marker reaction class recommender, diversity-oriented synthesis-based design, synthesis-based building block, and drug repositioning library has increased the use of computational tools. The use of these methodologies has led to an increase in the complexity of structural representation systems for which graph models have limitations in their generation, so that linear notation systems, such as SMILES, remain the means of choice for generating molecules in chemical libraries.