Proceedings of the 9th annual conference on Genetic and evolutionary computation

These proceedings contain the papers presented at the 9th Annual Genetic and Evolutionary Computation COnference (GECCO-2007), held in London, UK, July 7-11, 2007. For the first time GECCO was held outside the US. This clearly proved to be a success: a record number of 577 papers were submitted for review, an increase of nearly 30% when compared to last year. Of these 577 papers, 266 were accepted as an 8-page publication and a 25 minutes oral presentation at the conference. This represents an acceptance rate of 46.1%. In addition, 210 papers were accepted as poster presentation with a single-page abstract included in the proceedings. Initially, we had planned for two-page abstracts but the number of submissions made this impossible. We have reached the physical limit on the number of pages in 2-volume printed proceedings GECCO is a somewhat unusual conference with its concept of one conference, many mini-conferences. This year, there were 14 separate tracks that operated independently from each other. All tracks have their own track chair(s) and program committee. A member of a track's program committee is not allowed to simultaneously be a member of another track's committee. To reduce any bias reviewers might have all reviews were conducted double blind. No author's names were included in the reviewed papers. About 475 researchers participated in the reviewing process. Their work is much appreciated and it is absolutely vital for the quality of the conference GECCO-2007 welcomed two new tracks: one on Generative and Developmental Systems and another on Formal Theory. In addition to the presentation of the papers contained in these proceedings, GECCO-2007 also included 16 workshops, 41 free tutorials, a series of sessions on Evolutionary Computation in Practice, late-breaking papers, and awards in human-competitive results. The 21 track chairs deserve special thanks for their efforts in assembling their program committee, performing the paper assignments, and finally making the difficult acceptance or rejection decisions. Track chairs were not allowed to accept more than 50% of the track's submissions as full paper. This upper bound on the acceptance rate represents a healthy selection pressure in order to preserve the quality of the conference. In addition to the track chairs mentioned below a special word of thanks goes to Pat Cattolico whose help was invaluable for getting all the non-scientific issues right, and of course to Hod Lipson, the general chair of GECCO-2007