Kaye, R., R. Kossak and H. Kotlarski, Automorphisms of recursively saturated models of arithmetic, Annals of Pure and Applied Logic 55 (1991) 67-99. We give an examination of the automorphism groupâ€¦ (More)

One of the main goals in the study of the automorphism group Aut {Jt) of a countable, recursively saturated model Jt of Peano Arithmetic is to determine to what extent (the isomorphism type of) Jt isâ€¦ (More)

We define certain properties of subsets of models of arithmetic related to their codabili ty in end extensions and elementary end extensions. We characterize these properties using some more familiarâ€¦ (More)

We observe that the classification problem for countable models of arithmetic is Borel complete. On the other hand, the classification problems for finitely generated models of arithmetic and forâ€¦ (More)

/ Introduction Let L be the language of Peano Arithmetic (PA). If Mis a nonstandard model of PA then any arithmetization of L determines a nonstandard language Form (M), consisting of the formulas inâ€¦ (More)