Querying logical databases (Q579967)
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scientific article; zbMATH DE number 4016237
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | Querying logical databases |
scientific article; zbMATH DE number 4016237 |
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Querying logical databases (English)
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1986
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We study here the complexity of evaluating queries in logical databases. We focus on Reither's model of closed-world databases with unknown values. We show that in this setting query evaluation is harder than query evaluation for physical databases. For example, while 1st-order queries over physical databases can be evaluated in logarithmic space, evaluation of 1st-order queries in the studied model is co-NP-complete. We describe an approximation algorithm for query evaluation that enables one to implement a logical database on the top of a standard database management system.
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relational databases
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complexity of evaluating queries in logical databases
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closed-world databases with unknown values
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approximation algorithm
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database management
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