Genetic Programming 18th European Conference, EuroGP 2015, Copenhagen, Denmark, April 8-10, 2015, Proceedings - Machado, Penousal; Heywood, Malcolm I.; McDermott, James; Castelli, Mauro; García-Sánchez, Pablo; Burelli, Paolo; Risi, Sebastian; Sim, Kevin (Springer International Publishing : Imprint: Springer, 2015)