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The Essentially Equational Theory of Horn Classes

✍ Scribed by Hans-E. Porst

Publisher
John Wiley and Sons
Year
2000
Tongue
English
Weight
233 KB
Volume
46
Category
Article
ISSN
0044-3050

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✦ Synopsis

It is well known that the model categories of universal Horn theories are locally presentable, hence essentially algebraic (see ). In the special case of quasivarieties a direct translation of the implicational syntax into the essentially equational one is known (see ).

Here we present a similar translation for the general case, showing at the same time that many relationally presented Horn classes are in fact (equivalent to) quasivarieties.

πŸ“œ SIMILAR VOLUMES

On the Difference of Horn Theories
On the Difference of Horn Theories
✍ Thomas Eiter; Toshihide Ibaraki; Kazuhisa Makino πŸ“‚ Article πŸ“… 2000 πŸ› Elsevier Science 🌐 English βš– 248 KB

In this paper, we consider computing the difference between two Horn theories. This problem may arise, for example, if we take care of a theory change in a knowledge base. In general, the difference of Horn theories is not Horn. Therefore, we consider Horn approximations of the difference in terms o