Mathias Niepert Dirk Van Gucht Marc Gyssens On the Conditional Independence Implication Problem: A Lattice-Theoretic Approach. 435-443 2008 UAI http://uai2008.cs.helsinki.fi/UAI_camera_ready/niepert.pdf conf/uai/2008 db/conf/uai/uai2008.html#NiepertGG08