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The Essentially Equational Theory of Horn Classes
Author(s) -
Porst HansE.
Publication year - 2000
Publication title -
mathematical logic quarterly
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.473
H-Index - 28
eISSN - 1521-3870
pISSN - 0942-5616
DOI - 10.1002/(sici)1521-3870(200005)46:2<233::aid-malq233>3.0.co;2-i
Subject(s) - french horn , mathematics , translation (biology) , algebra over a field , syntax , pure mathematics , equational logic , linguistics , programming language , computer science , philosophy , rewriting , psychology , pedagogy , biochemistry , chemistry , messenger rna , gene
It is well known that the model categories of universal Horn theories are locally presentable, hence essentially algebraic (see [2]). In the special case of quasivarieties a direct translation of the implicational syntax into the essentially equational one is known (see [1]). 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.