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Dissertation
An analysis of redundant relationships in data and object modeling
Doctor of Philosophy (Ph.D.), Drexel University
1998
DOI:
https://doi.org/10.17918/00000671
Abstract
This research presents a complete analysis of structural validity and redundant relationships in the entity-relationship (ER) model. Direct treatment of structural validity and redundant relationships is rare in the literature. In practice there is no complete set of heuristics to holistically evaluate the structural validity or conclusively identify a redundant relationship in ER diagrams. Some validity rules are partly discussed in publications, but they do not exhaustively cover all the combinations of maximum and minimum cardinality and address only the most commonly used structures. Current approaches for identifying redundant relationships depend on the use of functional dependencies and do not consider minimum cardinality constraints. This omission disallows the inference of true transitive connectivity even with the presence of a related connection constraint. Existing approaches can only conclude that the relationship is "suspiciously redundant." In practice, this leaves the decision of removing a "suspiciously redundant" relationship to the subjective judgement of the designer. Our approach differs from previous works in that it: (1) Addresses both maximum and minimum cardinality constraints. (2) Considers the impact of ternary relationships on redundancy. (3) Presents a holistic analysis of unary, binary, and ternary relationships as they coexist in a complex overall diagram. (4) Treats structural validity and redundancy together. The study provides a thorough pattern analysis of redundant relationships and shows they are sufficiently determined by the cardinality constraints coupled with a semantic connection constraint. The analysis yields a comprehensive set of thirty decision rules to determine the structural validity and the redundancy of any unary, binary, and ternary relationship in a complex multi-path environment. These rules can easily be incorporated into the modeling process or extended into case tools implementations. This study extends previous works on ternary relationship validity to the areas of minimum cardinality constraints and the structural validity of a complete diagram where a ternary relationship coexists. This study lays a foundation in the analysis of structural validity and relationship redundancy in object modeling. We have shown that the analysis rules identified for data modeling are readily adaptable for the analysis of redundancy in object modeling with association, aggregation, and inheritance constructs.
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Details
- Title
- An analysis of redundant relationships in data and object modeling
- Creators
- James A. Dullea
- Contributors
- Il-Yeol Song (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xiii, 201 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Information Science and Technology (1995-2013); Drexel University
- Other Identifier
- 991014970323804721