Genetic Programming 22nd European Conference, EuroGP 2019 : held as part of EvoStar 2019, Leipzig, Germany, April 24–26, 2019 : proceedings - Sekanina, Lukas; Hu, Ting; Lourenço, Nuno; Richter, Hendrik; García-Sánchez, Pablo (Lecture notes in computer science, 2019)