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Generalized quantifiers in algebra. (English) Zbl 0905.03029

Krynicki, Michał(ed.) et al., Quantifiers: logics, models and computation. Volume two: Contributions. Dordrecht: Kluwer Academic Publishers. Synth. Libr. 249, 215-228 (1995).
Logics with certain generalized quantifiers are constructed in this paper. The introduced quantifiers allow to study lattices of congruences and lattices of subalgebras. The formulas of the languages \(L_{\omega\omega}(\approx)\) and \(L_{\omega\omega}(\langle\;\;\rangle)\) are inductively defined and both have the Skolem-Löwenheim property. The Hanf number of \(L_{\omega\omega}(\approx)\) is equal to the Hanf number of \(L_{\omega\omega}(\langle\;\;\rangle)\). Both languages are neither compact nor axiomatizable. The theory of a finitely generated discriminator variety is decidable in the language \(L_{\omega\omega}(\approx)\), but the theory of a non-locally finite variety of Abelian groups is undecidable in \(L_{\omega\omega}(\approx)\) as well as in \(L_{\omega\omega}(\langle\;\;\rangle)\). Finally, the author mentions similar results on the languages \(L_{\omega\omega}({\mathbf A})\) and \(L_{\omega\omega}(\equiv)\) concerning the automorphism quantifier \({\mathbf A}\) and the quantifier \(\equiv\) of elementary equivalence, respectively.
For the entire collection see [Zbl 0885.00035].

MSC:

03C80 Logic with extra quantifiers and operators
08A30 Subalgebras, congruence relations
03C60 Model-theoretic algebra
03B25 Decidability of theories and sets of sentences
08B10 Congruence modularity, congruence distributivity