Authors: Marianne Winslett
Tags: 1995, conceptual modeling, Vânia M. P. Vidal
A problem of schema integration is that one cannot directly merge concepts that are intuitively the same but have different representations. This problem can be solved by performing schema transformations to conform the views being integrated so that merging of classes and attributes becomes possible (schema restructuring). Previously, researchers have approached schema restructuring in an informal manner, offering heuristics to guide practitioners during integration; thus a formal underpinning for schema restructuring has not yet been established. To establish a formal underpinning, one must extend current methodologies for schema integration to be able to express the equivalence of concepts that have nonidentical representations. Such expressive power is needed to be able to formally justify the correctness of the transformations that are used during schema restructuring. Our work addresses this problem by supporting more general forms of existence dependency constraints which allow the formal definition of the most common types of transformations that are required during schema restructuring. In this paper we formally define a decomposable normal form for schemas that specifies which properties a schema should have so that certain technical problem of concept merging do not occur. We also present an algorithm to transform a schema into an equivalent schema which is in decomposable normal form.Read the full paper here: https://link.springer.com/chapter/10.1007/BFb0020524
