Entity semantic model

Abstract

This thesis studies database operations on the entity level in the semantic data model including is-a hierarchy. As a new class interrelationship among those entities which represent composite concepts, entitysharable relationship is identified. The is-a hierarchy is further classified into four cases-conceptual, attributedefined, set-operated, existence-constrained is-a. For each case, a richer set of invariants to support database operations is explored. These class relationships suggest some postulates for joinable conditions which can prevent meaningless joins.