Towards multi-level and modular conceptual schema specifications
Information Systems
Automatic correction to misspelled names: a fourth-generation language approach
Communications of the ACM
Extending the database relational model to capture more meaning
ACM Transactions on Database Systems (TODS)
Object Class Definition by Generalization Using Upward Inheritance
Proceedings of the Fourth International Conference on Data Engineering
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The existing models for database applications use a few fundamental concepts for the description of the world to be modeled. The most common of these concepts is the entity, also called object, element, concept, information, token, data or value. Entities are identifiable and distinguishable existing things of the real world. In general the concept of entity, is used only for static things whose existence does not depend directly from other entities, in contrast to the dynamic happenings called events and the existence of some dependency between two or more entities called relationship (or attribute or property) which can exist only in conjunction with the related entities. More complex combinations of entities, relationships and events we call facts. Therefore “John has broken his leg yesterday and is in Santa Clara Hospital” is a fact which combines the event of “breaking a leg” occurred with the entity “leg of John” at time-event “yesterday” and the relationship “is in” valid between “John” and “Santa Clara Hospital” now. We use the term object to refer to entities, relationships, events or facts, undistinguishably.