Claudio Vaucheret Sergio Guadarrama Susana Muñoz-Hernández Fuzzy Prolog: A Simple General Implementation Using CLP(R). 450-464 2002 conf/lpar/2002 LPAR http://link.springer.de/link/service/series/0558/bibs/2514/25140450.htm db/conf/lpar/lpar2002.html#VaucheretGM02