Erik D. Demaine Francisco Gomez-Martin Henk Meijer David Rappaport Perouz Taslakian Godfried T. Toussaint Terry Winograd David R. Wood http://arxiv.org/abs/0705.4085 2007 CoRR abs/0705.4085 db/journals/corr/corr0705.html#abs-0705-4085 informal publication