For a class of extensions of free products of groups, a description is given of the space of the real-valued functions Ο defined on the group G and satisfying the conditions (1) the set Ο xy -Ο x -Ο y x y β G is bounded; and (2) Ο x n = nΟ x for any x β G and any n β (the set of integers). Let G be
Expressibility and the problem of efficient text planning
β Scribed by John A. Bateman
- Publisher
- Springer
- Year
- 1996
- Tongue
- English
- Weight
- 598 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0922-6567
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## Abstract We investigate why similar extensions of firstβorder logic using operators (that is, generalized quantifiers) corresponding to NPβcomplete decision problems apparently differ in expressibility: the logics capture either NP or L^NP^. It had been conjectured that the complexity class capt
The work of Chandra and Harel contained in Chandra and Harel (J. Comput. System Sci. 21 (1980) 156 -178) can be considered as the beginning of the construction of a theoretical framework in which the computability and the complexity of queries to relational databases could be studied. In the deΓΏniti