AI.ELLIE@MCC.COM (Ellie Huck) (05/15/87)
Please join the AI Program for the following talk:
Gert Smolka
Universitat Kaiserslauten
May 20 - 2:00pm
AI Conference Room 2.502
"Inheritance Hierarchies: Semantics and Unification"
Inheritance hierarchies are employed in knowledge representation and
object-oriented programming as a means of representing taxonomically
organized data. In our approach, inheritance hierarchies are built up
from so-called feature types, which are ordered by subtyping and whose
elements are records. Every feature type comes with a set of features
corresponding to the fields of its record elements.
Given an inheritance hierarchy, so-called feature terms are used to
denote sets of values. Unification of two feature terms computes a
feature term denoting the intersection of their denotations. Feature
unification is employed in logic programming and computational
linguistics.
In this talk, we express feature types and inheritance hierarchies as
algebraic types in order-sorted equational logic. This reduction
provides a meaningful initial algebra semantics and a well understood
notion of equality. In particular, our framework supports the
combination of algebraic types and inheritance hierarchies.
Feature unification turns out to be unification with respect to
equational axioms and to subsume order-sorted and untyped unification.
We specify a unitary feature unification algorithm by a set of
simplification rules and prove its soundness and completeness with
respect to the model-theoretic semantics.
May 20 - 2:00pm
AI Conference Room 2.502
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