Chengqi Zhang Shichao Zhang Zili Zhang Temporal Constraint Satisfaction in Matrix Method. 135-154 2003 17 Applied Artificial Intelligence 2 http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=0883-9514&volume=17&issue=2&spage=135 db/journals/aai/aai17.html#ZhangZZ03