Journal of Logic and Computation 11(4),
Nonmonotonic Inheritance in Object-Oriented
Deductive Database Languages
Wolfgang May, Paul-Thomas Kandzia
Deductive object-oriented frameworks integrate logic rules and
inheritance. There, specific problems arise: Due to the combination
of deduction and inheritance, (a) deduction can take place depending
on inherited facts, thus raising indirect conflicts, and (b) also
the class hierarchy and -membership is subject to deduction.
From this point of view, we investigate the application of the
extension semantics of Default Logic to deductive object-oriented
By restricting the problem to Horn programs and a special type of
defaults tailored to the semantics of inheritance, a
forward-chaining construction of a Herbrand-style representation of
extensions is possible.
This construction is compared with the semantics defined in
[KLW95] for F-Logic (and implemented in the
which is based on a combination of classical deductive fixpoints and
an inheritance-trigger mechanism. We show that the F-Logic semantics
coincides with the standard semantics of Default Logic and Inheritance Networks.
Preliminary versions have been presented in