Gabriel Aranda-López Susana Nieva Fernando Sáenz-Pérez Jaime Sánchez-Hernández Implementing a fixed point semantics for a constraint deductive database based on hereditary harrop formulas. 117-128 2009 PPDP http://doi.acm.org/10.1145/1599410.1599426 conf/ppdp/2009 db/conf/ppdp/ppdp2009.html#Aranda-LopezNSS09