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ABSTRACT
Temporal functional dependencies (TFD) are defined
for temporal databases that include object identity. It is argued that object identity can overcome certain semantic diffuculties with existing temporal relational data models. Practical applications of TFDs in object bases are discussed. Reasoning about TFDs is at the center of this paper. It turns out that the distinction between acyclic and cyclic schemas is significant. For acyclic schemas, a complete axiomatization for finite implication is given and an algorithm for deciding finite implication provided. The same axiomatization is proven complete for unrestricted implication in unrestricted schemas, which can be cyclic. An interesting result is that there are cyclic schemas for which unrestricted and finite implication do not coincide. TFDs relate and extend some earlier work on dependency theory in temporal databases. Throughout this paper, the construct of TFD is compared with the notion of temporal FD introduced by Wang et al. (1997). A comparison with other related work is provided at the end of the article.
REFERENCES
Note: OCR errors may be found in this Reference List extracted from the full text article. ACM has opted to expose the complete List rather than only correct and linked references.
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CITED BY 12
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Jef Wijsen , Raymond T. Ng , Toon Calders, Discovering roll-up dependencies, Proceedings of the fifth ACM SIGKDD international conference on Knowledge discovery and data mining, p.213-222, August 15-18, 1999, San Diego, California, United States
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Lukasz Golab , Theodore Johnson , Nick Koudas , Divesh Srivastava , David Toman, Optimizing away joins on data streams, Proceedings of the 2nd international workshop on Scalable stream processing system, March 29-29, 2008, Nantes, France
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