Forcing infinito generalizzato in teoria dei modelli
Proprietà metamatematiche di alcune classi di algebre
Questioni di teoria dei modelli per linguaggi universali positivi. II: Metodi di "back and forth"
In this paper we continue the investigations of a previous one, givinga back and forth characterization of L—equivalence, where L is an universal positive (u.p.)language. The key idea is to use partial abridgments in place of partial isomorphisms. This allows us to proceed in the same way as in the classical characterization of elementary equivalence. These results and those (1) by Barwise and Schlipf on recursively saturated models are used to get a Robinson Consistency Theorem for u.p. and negation...
Sull'aggiunto del funtore dimenticante tra due classi equazionali
In this paper the following result is proved: let be an equational class (variety) of algebras of type and let be an equational class of algebras of type with and , then the canonical forgetful functor admits a left adjoint.
On the congruence lattice of stable algebras with definability of compact congruences
Questioni di teoria dei modelli per linguaggi universali positivi
In this paper some model theoretical notions for universal positive languages are investigated. In §i and §2 we shall study the lattice of formulas, maximal and prime theories, and correlations between them. In §3, §4 we shall define some kind of morphisms and we shall characterize theories with quantifier elimination.
Page 1