Editorial to tenth anniversary issue on progress in genetic programming and evolvable machines

The Genetic Programming and Evolvable Machines journal is 10 years old. This sizable special issue is intended to mark this special anniversary and take the opportunity to look back at what has been achieved in the last 10 years of Genetic Programming (GP) and to start charting the terrain for potential new developments in the next 10 years. When putting together this special issue, we were particularly interested in high quality papers that reviewed or analysed progress in the field, presented the state-ofthe-art in the evolution of software and hardware, described promising new approaches and paradigms, suggested important new application areas, or provided an in-depth coverage of foundational topics and theoretical analyses in genetic programming and evolvable machines. Three articles were invited to act as reference points for the special issue: one on theoretical results in GP, a review of human-competitive applications of GP and one aimed at providing a snapshot of the published literature in GP. We then encouraged submissions that would complement these seeds thereby providing a full coverage of the topics we aimed for in this special issue. Twelve further papers were obtained through the open submission process. We would like to thank their authors for their willingness to contribute to this special issue. Some of the papers submitted, while very good contributions to the field, did not have the necessary breadth for inclusion in this special issue. These were thus