Frank Dylla Alexander Ferrein Gerhard Lakemeyer Jan Murray Oliver Obst Thomas Röfer Frieder Stolzenburg Ubbo Visser Thomas Wagner Towards a League-Independent Qualitative Soccer Theory for RoboCup. 611-618 http://dx.doi.org/10.1007/978-3-540-32256-6_58 2004 conf/robocup/2004 RobuCup db/conf/robocup/robocup2004.html#DyllaFLMORSVW04