The Rule Interchange Format (RIF) is the third building block of the infrastructure for the Semantic Web, along with SPARQL, RDF, and OWL. Although originally envisioned by many as a rules layer for the Semantic Web, in reality the design of RIF is based on the observation that there are many rules languages in existence, and what is needed is to exchange rules between them. An action is different from the conclusion of a logic rule, which contains only a logical statement. Datalog is a rule and query language for deductive databases that syntactically is a subset of Logic Programs and became prominent as a separate area around 1977 when Herve Gallaire and Jack Minker organized a workshop on logic and databases. Similarly to DLs, we may extend Datalog with concrete domains, to deal with datatypes, such as strings and integers. SLD-Resolution (Selective Linear Definite clause resolution) is the basic inference rule used in logic programming.