http://doi.acm.org/10.1145/317426.317443 Paul Smolensky Brigham Bell Barbara Fox Roger King Clayton H. Lewis Constraint-Based Hypertext for Argumentation. 215-245 HT1987/P215.pdf 1987 conf/ht/87 Hypertext db/conf/ht/ht87.html#SmolenskyBFKL87