On the Semantics of a Semantic Network

We elaborate on the semantics of an enhanced object oriented semantic network where multiple instantiation multiple specialization and meta classes are supported for both kinds of objects entities and properties By semantics of a semantic network we mean the information both explicit and derived that the semantic network carries Several data models use semantic networks to organize information However many of these models do not have a formalism de ning what the semantics of the semantic network is In our data model in addition to the Isa relation we consider a stronger form of specialization for properties that we call restriction isa or Risa for short The Risa relation expresses property value re nement A distinctive feature of our data model is that it supports the interaction between Isa and Risa relations The combination of Isa and Risa provides a powerful conceptual modeling mechanism Research conducted while this author was visiting with the Institute of Computer Science Foundation for Research and Technology Hellas The user declares objects and relations between objects through a program Reasoning is done through a number of built in inference rules that allow for derivations both at instance and schema level Through the inference rules new objects and new relations between objects are derived In our data model inherited properties are considered to be derived objects In addition to the inference rules a number of built in system constraints exist for checking the validity of a program