Abstract:
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We present a visual language expressive enough to capture an
important subset of First Order Predicate Logic as well as its straightforward translation to the logic-based paradigm of deductive databases. We use the diagrams of our language to represent all the
components of a deductive database schema: base predicates, derived
predicates with their deductive rules, and integrity constraints.
Our diagrams are grounded on two powerful visual metaphors:
Venn/Euler diagrams and graphs, familiar to most designers; they are formal and independent of the application domain; they emphasize
basic forms of logic description, the diagrammatic syntax being
closer to the semantics; and they have a simple translation to
Horn clauses. Thus, we aim at a situation where the generality of deductive databases would be fostered by the expected greater
usability of visual schema languages in the hands of a wider
group of practitioners. |