Learning Classifier Systems : 11th International Workshop, IWLCS 2008, Atlanta, GA, USA, July 13, 2008, and 12th International Workshop, IWLCS 2009, Montreal, QC, Canada, July 9, 2009, Revised Selected Papers - Jaume Bacardit, Will Browne, Jan Drugowitsch, Ester Bernadó-Mansilla, Martin V. Butz ((Lecture Notes in Computer Science))