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Artículo
On axiom schemes for T-provably Δ1 formulas
(Springer, 2014)
This paper investigates the status of the fragments of Peano Arithmetic obtained by restricting induction, collection and least number axiom schemes to formulas which are Δ1 provably in an arithmetic theory T. In ...
Artículo
Existentially Closed Models in the Framework of Arithmetic
(The Association for Symbolic Logic, 2016)
We prove that the standard cut is definable in each existentially closed model of IΔ0 + exp by a (parameter free) П1–formula. This definition is optimal with respect to quantifier complexity and allows us to improve some ...