Shared conceptual schema for four medical expert systems

The fundamental reason for database management systems is the support of applications using shared overlapping sets of data through external views of an underlying conceptual schema. The definition of such a schema for expert systems (ESs) is a topic of interest to database researchers both as a proof that ESs can be supported and as an exploration of the process of view integration. A shared conceptual schema has been constructed for four widely known medical ESs, and can be mapped to the knowledge base of each using seven operations: COMPOSE, FILTER, FOLD, UNFOLD, CONTRACT, RENAME, and CONSTRAIN. The schema and mappings show features the ESs share, such as rules and patterns, and features that distinguish them, such as a unique form of diagnosis. The schema's content shows a lack of structural, temporal, or strategic information and illustrates how the types and relationships of shell-like systems are hidden in instances and must be interpreted by program code.