DLV is a system for disjunctive datalog with constraints, true negation
and queries.

The DLV system also includes

    * the K planning system,
    * a frontend for abductive diagnosis and Reiter's diagnosis,
    * support for inheritance, and
    * an SQL frontend which prototypes some novel SQL3 features.

WWW:	http://www.dbai.tuwien.ac.at/research/project/dlv/