Abstract
In complex object oriented databases, the purpose of introducing class hierarchy is to express ISA semantics, to realize inheriting and to reuse schema definition codes. The schema definition and schema evolution, based on the partial order of lattice, often cause the loss of information inheriting and the redundance of schema definition. Based on the fullness of the inheritance shown by class hierarchy, three normal forms of class hierarchy are given in this paper, and a general algorithm of normalization of class hierarchy is presented, following the Boolean algebra model of class hierarchy. The loss of information inheritance can be avoided when they are applied to schema design and schema evolution.
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References
Abiteboul Set al. Objects and Views. InProc. of SIGMOD, 1991.
Alhajj R, Arkun M. A query model for object-oriented database. InIEEE Int’l. Conf on Data Engineering, 1993.
Bancilhon F, Khoshafian S. A Calculus for Complex Objects. ACM-SIGMOD-SIGACTSIGART, 1986.
Bancilhon Fet al. Building an Object-Oriented Database System, the Story ofO 2. Morgan Kaufmann Publishers, 1992.
Herer A, Sander P. Classifying Object-Oriented Query Results in a Class/Type Lattice. InProc. of EDBT, 1990.
Kim W. Introduction to Object-Oriented Database. The MIT Press, 1990.
Ossher H, Harrison W. Combination of Inheritance Hierarchies. InProc. of OOPSLA, 1992.
Tremblay J P, Manohar R. Discrete Mathematical Structures with Applications to Computer Science. McGraw-Hill Book Company, 1975.
Zdonik S B. Object-Oriented Type Evolution. InAdvances in Programming Language, Bancilhon Fet al. (eds.), 1990.
Chen Qiming. A general structure model for object and type in database system.Chinese Journal of Computer Science, 1989, (8).
Gu Xinshenget al. The theory of object-oriented semantics relationship data model.Chinese Journal of Software, 1993, (5).
Li Tianzhu. Strong and weak semantics relationship. InProceeding of 11th National Conference on Database in China, 1993.
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The research is supported by The National Natural Science Foundation of China and The Natural Science Foundation of Hebei Province.
Li Tianzhu graduated from Department of Mathematics at Hebei University in 1965, and joined the faculty of the University. In 1987, he became an Associate Professor. He was in University of Pittsburgh as a visiting scholar working on database and knowledge base in 1990. Now he is a Professor at Hebei University. His research interests include database, knowledge base and information systems.
Xiao Jitian received his B.S. degree from Department of Mathematics at Hebei University in 1982, and his M.E. degree in computer science at National University of Defence Technology in 1989. Now, he is an Associate Professor of Department of Electronics and Information Engineering, Hebei University. His research interests include object-oriented methodoloty, database, computer graphics and multimedia application.
Sun Zhaohao reveived his B.S. and M.S. degrees from Department of Mathematics at Hebei University in 1982 and 1994, respectively. He is now a Lecturer of Department of Electronics and Information Engineering in Hebei University. His research interests include artificial intelligence and database.
Bian Xiaofan graduated from Department of Electronics Engineering at Tsinghua University in 1974. Now he is a Senior Engineer of Computer Center at Hebei University. His research interests include information system, database and computer network.
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Li, T., Xiao, J., Sun, Z. et al. Normalization of class hierarchy in databases. J. of Comput. Sci. & Technol. 11, 356–364 (1996). https://doi.org/10.1007/BF02948479
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DOI: https://doi.org/10.1007/BF02948479