Volker Weispfenning Semilinear Motion Planning in REDLOG. 455-475 2001 12 Appl. Algebra Eng. Commun. Comput. 6 http://link.springer.de/link/service/journals/00200/bibs/1012006/10120455.htm db/journals/aaecc/aaecc12.html#Weispfenning01