Parallel problem solving from nature – PPSN XV 15th International Conference, Coimbra, Portugal, September 8-12, 2018 : proceedings, part I - Auger, Anne; Fonseca, Carlos M. da 1968-; Lourenço, Nuno; Machado, Penousal; Paquete, Luís F.; Whitley, L. Darrell (Springer, 2018)