Ruiz-Vanoye, .J.A., Díaz-Parra, O., Trejo-Macotela, F.R. and Ramos-Fernández, J.C. 2020. Editorial: P versus NP problem from Formal Languages Theory View. International Journal of Combinatorial Optimization Problems and Informatics. 12, 1 (Dec. 2020), 1–8.