Reinhard Moratz Bernhard Nebel Christian Freksa Qualitative Spatial Reasoning about Relative Position: The Tradeoff between Strong Formal Properties and Successful Reasoning about Route Graphs. 385-400 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2685&spage=385 2003 conf/spatialCognition/2003 Spatial Cognition db/conf/spatialCognition/spatialCognition2003.html#MoratzNF03