@article {DBLP:journals/ai/SkiadopoulosK05,
	title = {On the consistency of cardinal direction constraints},
	journal = {Artif. Intell.},
	volume = {163},
	number = {1},
	year = {2005},
	pages = {91{\textendash}135},
	doi = {10.1016/j.artint.2004.10.010},
	url = {https://doi.org/10.1016/j.artint.2004.10.010},
	author = {Spiros Skiadopoulos and Manolis Koubarakis}
}
