The Declarative Toolkit Declare and
the Deductive Database System DDBase
Prof. Dr. Dietmar Seipel
Declare (formerly DDK, DisLog Developers' Kit)
is a collection of libraries developed in SWI-Prolog
including features from data and knowledge engineering,
databases (relational, XML, deductive), Semantic Web,
and non-monotonic reasoning;
DDBase is part of Declare, too.
The Declarative Toolkit Declare
The Declare project started with a system
for non-monotonic reasoning in disjunctive deductive databases.
A variety of additional packages for different purposes has been added, e.g.
Most applications are equipped with graphical user interfaces
developed in object-oriented (e.g., Java or the
extension XPCE of SWI-Prolog) or in declarative markup languages
(e.g., HTML 5 or the XML User Interface Language XUL from
the Mozilla project).
Declare can be downloaded from
(about 9 MB).
The Deductive Database System DDBase
DDBase uses the Datalog extension Datalogs with function symbols,
where rule bodies can contain embedded Prolog calls and default negation.
Bottom-up and top-down evaluation are possible in one system:
Datalogs can evaluate extended Datalog programs,
i.e. logic programs with Prolog syntax, in a bottom-up style;
it is designed to evaluate embedded Prolog calls in a
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