Self-embeddings of models of arithmetic; fixed points, small submodels, and extendability

Saeideh Bahrami

In this paper we will show that for every cut $I$ of any countable nonstandard model $\mathcal{M}$ of $\mathrm{I}{\Sigma }_1$, each $I$-small ${\Sigma }_1$-elementary submodel of $ \…