The Declare Developers' Toolkit DDK and
the Deductive Database System DDBase

by Dietmar Seipel

Declare is a collection of libraries for declarative programming including features from developed in SWI-Prolog. The deductive database system DDBase is part of the Declare.


The Declare project started with building a system DisLog for non-monotonic reasoning in disjunctive deductive databases. In the meantime a variety of additional packages for different purposes has been implemented: Most of the packages are equipped with graphical user interfaces, that have been developed in the object-oriented extension XPCE of SWI-Prolog.

Declare can be obtained as a tgz-archive (of about 9 MB) at


DDBase uses the extension Datalogs of Datalog with function symbols. Rule bodies can contain embedded Prolog calls and default negation.

It is possible to have bottom-up and top-down evaluation in one system. Datalogs can evaluate logic programs with Prolog syntax (extended Datalog programs) in a bottom-up style; it is designed to evaluate embedded Prolog calls in a top-down manner.

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