Abstract
Structured objects have components which can be unknown at a given time. This kind of incomplete information is represented using special constants: Skolem constants, which cannot be handled as usual constants with the Relational Algebra. For this purpose we define the semantics associated with this kind of information by theories Ts whose axioms have a specific form. Since deduction in a theory is much more expensive than algebraic evaluation in a model, we define a specific kind of Extended Model, EMy having the same semantics as a theory TSy and an Extended Relational Algebra to efficiently compute answers to queries in this Extended Model, EM. It is shown that this algebra is always sound, and that it is complete for a specific class of queries which can contain disjunctions and/or negations.
This work was partially supported by the ESPRIT project P316:ESTEAM.
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© 1989 Springer-Verlag Berlin Heidelberg
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Demolombe, R., del Cerro, L.F. (1989). Efficient Representation of Incomplete Information About Structured Objects. In: Schmidt, J.W., Thanos, C. (eds) Foundations of Knowledge Base Management. Topics in Information Systems. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-83397-7_4
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DOI: https://doi.org/10.1007/978-3-642-83397-7_4
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