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On syntax and semantics related to incomplete information databases

Show simple item record Orlowska, M.E. 2018-06-06T14:03:36Z 2018-06-06T14:03:36Z 1988
dc.identifier.citation MEOrlowska (1988) On syntax and semantics related to incomplete information databases. Quaestiones Informaticae Vol 6 No 2 1988 en
dc.identifier.issn 0254-2757
dc.description.abstract We propose a mathematical model of a database with incomplete information, which we call the N-system. Basically speaking, such a system stores information concerning properties of some objects. The information may be incomplete in that it may be known that the object has a property with probability from the interval <a,[3> c <0,1>. In the particular case where <a,[3>=<0,1>, means that it may be not known whether an object has a property, the N-system is equivalent to Lipski' s system [3]. In another particular case, when <a,[3>=<1,1> or <a,{3>=<0,0> the N-system presented corresponds to Codd' s relational model of databases []]. The first level, the level of terms of a query language to communicate with the N-system, is described and its semantics and syntax are defined. A system of axioms, which serves as a basis/or equivalent transformations of queries is presented ( only for terms). Syntactical and semantic equivalences for terms are defined and completeness properties are shown. en
dc.language.iso en en
dc.publisher Computer Society of South Africa (on behalf of SAICSIT) en
dc.title On syntax and semantics related to incomplete information databases en
dc.type Article en
dc.description.department School of Computing en

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