Integration von Sorten
als ausgezeichnete taxonomische
in eine relational-funktionale Sprache
Sorts are incorperated into RELFUN as distinguished unary predicates usable
as first-class citizens.
Inheritance is integrated into the unification process via a
taxonomy defined by a partial-order relation on the sorts. Sort knowledge
describes which individuals belong to a sort (ABOX) and which order
dependencies exist between the sorts (TBOX). This special knowledge should
be recognizable as such. The seperation can be reached by a special
(second-order) predicate subsumes or by partitioning the knowledge base.
Focusing on partitioning, we can choose a dynamic (run-time) or static
(compile-time) model for the unification involving sorted terms. In the static
model a precompiler generates an internal structure representing the
reflexive-transitive sort closure and the defined individuals of each sort.
Using this structure, unification is reduced to list intersectiom (sort-sort
unification, succeeding with the glb) or a membership test (sort-individual
unification). It also provides elementary validation operations for
taxonomy acylicity, unique glb's, and the equivalence of intensional (TBOX)
and exensional (ABOX) glb's.