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://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3276&spage=611 2004 conf/robocup/2004 RobuCup db/conf/robocup/robocup2004.html#DyllaFLMORSVW04