Sanjiang Li Weiming Liu 0001 Sheng-Sheng Wang 0001 Qualitative constraint satisfaction problems: An extended framework with landmarks. 32-58 2013 201 Artif. Intell. https://doi.org/10.1016/j.artint.2013.05.006 https://www.wikidata.org/entity/Q62042737 db/journals/ai/ai201.html#LiLW13