## Arithmetically saturated models of arithmetic.(English)Zbl 0848.03017

A model of a first-order theory is arithmetically saturated if it is saturated with respect to the types that are arithmetic in the complete types realized in the model. The paper presents an outline of the general theory of countable arithmetically saturated models of PA and some of its applications. The results concern the automorphism group of a countable recursively saturated model of PA. New results on fixed point sets, open subgroups, and the cofinality of the automorphisms group are given. It is also shown that the standard system of a countable arithmetically saturated model of PA is determined by the lattice of the elementary substructures of the model.

### MSC:

 03C62 Models of arithmetic and set theory 03C50 Models with special properties (saturated, rigid, etc.)
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### References:

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