Conservativity of Nested Relational Calculi with Internal Generic Functions (1994)
| Venue: | Information Processing Letters |
| Citations: | 22 - 16 self |
BibTeX
@INPROCEEDINGS{Libkin94conservativityof,
author = {Leonid Libkin and Limsoon Wong},
title = {Conservativity of Nested Relational Calculi with Internal Generic Functions},
booktitle = {Information Processing Letters},
year = {1994},
pages = {273--280}
}
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Abstract
It is known that queries in nested relational calculus are independent of the depth of set nesting in the intermediate data and this remains true in the presence of aggregate functions. We prove that this continues to be true if the calculus is augmented with any internal generic family of functions. 1 Introduction Paredaens and Van Gucht [7] proved that the nested relational calculus is no more expressive than the traditional relational calculus when input and output are flat relations. That is, every query on input and output whose depth of set nesting is at most 1 (or flat relations) can be expressed without using any intermediate data whose depth of set nesting is greater than 1. This result was generalized by Wong [10] who showed that every query on input and output whose depth of set nesting is at most k can be expressed without using any intermediate data whose depth of set nesting is greater than k. Hence the expressive power of the nested relational calculus is independent o...
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