Jochen Renz Qualitative Spatial and Temporal Reasoning: Efficient Algorithms for Everyone. 526-531 2007 conf/ijcai/2007 IJCAI http://dli.iiit.ac.in/ijcai/IJCAI-2007/PDF/IJCAI07-083.pdf db/conf/ijcai/ijcai2007.html#Renz07