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TWO-VARIABLE LOGIC HAS WEAK, BUT NOT STRONG, BETH DEFINABILITY

Published online by Cambridge University Press:  01 February 2021

HAJNAL ANDRÉKA
Affiliation:
SET THEORY, LOGIC AND TOPOLOGY DEPARTMENT ALFRÉD RÉNYI INSTITUTE OF MATHEMATICS BUDAPEST, REÁLTANODA ST. 13–15, H-1053, HUNGARYE-mail:[email protected]:[email protected]
ISTVÁN NÉMETI
Affiliation:
SET THEORY, LOGIC AND TOPOLOGY DEPARTMENT ALFRÉD RÉNYI INSTITUTE OF MATHEMATICS BUDAPEST, REÁLTANODA ST. 13–15, H-1053, HUNGARYE-mail:[email protected]:[email protected]

Abstract

We prove that the two-variable fragment of first-order logic has the weak Beth definability property. This makes the two-variable fragment a natural logic separating the weak and the strong Beth properties since it does not have the strong Beth definability property.

Type
Article
Copyright
© The Association for Symbolic Logic 2021

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References

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