Issue No.07 - July (1985 vol.11)
A.M. Keller , Department of Computer Science, Stanford University
In this paper we consider approaches to updating databases containing null values and incomplete information. Our approach distinguishes between modeling incompletely known worlds and modeling changes in these worlds. As an alternative to the open and closed world assumptions, we propose the expanded closed world assumption. Under this assumption, we discuss how to perform updates on databases containing set nulls, marked nulls, and simple conditional tuples, and address some issues of refining incompletely specified information.
updates, Databases, incomplete information, null values, relational databases
A.M. Keller, M.W. Wilkins, "On the Use of an Extended Relational Model to Handle Changing Incomplete Information", IEEE Transactions on Software Engineering, vol.11, no. 7, pp. 620-633, July 1985, doi:10.1109/TSE.1985.232506