منابع مشابه
Preservation properties in deductive databases
This paper constitutes a brief study of the following scheme DAΓ of default reasoning: Given set of premises Σ, assume φ if and only if, for every γ ∈ Γ, Σ ∪ {φ} does not entail γ unless Σ does, where Γ and Σ are sets of clauses, and φ is a clause. The problem of ∀-completeness of DAΓ with respect to nest model semantics is investigated. A method of deriving ∀-completeness of DAΓ1∩Γ2 assuming D...
متن کاملNon-Determinism in Deductive Databases
This paper examines the problem of adding non-deterministic constructs to a declarative database language based on Horn Clause Logic. We revise a previously proposed approach, the choice construct introduced by Krishnamurthy and Naqvi, from the viewpoints of amenability to efficient implementation and expressive power. Thus, we define a construct called dynamic choice, which is consistent with ...
متن کاملAggregation in Disjunctive Deductive Databases
Practical applications of deductive databases often require the use of extended features like disjunctive information, aggregation operators or default negation. But it has been unclear how one could deal with aggregation in the presense of recursion and disjunction. Usually , there is the requirement that deductive databases must be stratiied w.r.t. aggregation, i.e. a predicate q that is deen...
متن کاملTemporal Deductive Databases
We survey a number of approaches to the problem of nite representation of innnite temporal extensions. Two of them, Datalog 1S and Templog, are syntactical extensions of Datalog; the third is based on repetition and arithmetic constraints. We provide precise characterizations of the expressiveness and the computational complexity of these languages. We also describe query evaluation methods.
متن کاملTowards Deductive Object Databases
This paper proposes a new approach to model deductive object databases. Each object database is described by means of a Datalog language extended with extensional updates, called U-Datalog. Objects can change state and cooperate. We introduce an extension of U-Datalog to approach the problem of composition among object databases. It can be used for modular database design and for cooperation am...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: The Journal of Logic Programming
سال: 1988
ISSN: 0743-1066
DOI: 10.1016/0743-1066(88)90006-4