## Journal of Symbolic Logic

### Model Companions for Finitely Generated Universal Horn Classes

Stanley Burris

#### Abstract

In an earlier paper we proved that a universal Horn class generated by finitely many finite structures has a model companion. If the language has only finitely many fundamental operations then the theory of the model companion admits a primitive recursive elimination of quantifiers and is primitive recursive. The theory of the model companion is $\aleph_0$-categorical iff it is complete iff the universal Horn class has the joint embedding property iff the universal Horn class is generated by a single finite structure. In the last section we look at structure theorems for the model companions of universal Horn classes generated by functionally complete algebras, in particular for the cases of rings and groups.

#### Article information

Source
J. Symbolic Logic, Volume 49, Issue 1 (1984), 68-74.

Dates
First available in Project Euclid: 6 July 2007

Permanent link to this document
https://projecteuclid.org/euclid.jsl/1183741476

Mathematical Reviews number (MathSciNet)
MR736604

Zentralblatt MATH identifier
0599.03033

JSTOR
links.jstor.org

#### Citation

Burris, Stanley. Model Companions for Finitely Generated Universal Horn Classes. J. Symbolic Logic 49 (1984), no. 1, 68--74. https://projecteuclid.org/euclid.jsl/1183741476