September 9
Saeideh Bahrami, Institute for Research in Fundamental Sciences, Tehran
Fixed Points of Initial Self-Embeddings of Models of Arithmetic

In 1973, Harvey Friedman proved his striking result on initial self-embeddings of countable nonstandard models of set theory and Peano arithmetic. In this talk, I will discuss my joint work with Ali Enayat focused on the fixed point set of initial self-embeddings of countable nonstandard models of arithmetic. Especially, I will survey the proof of some generalizations of well-known results on the fixed point set of automorphisms of countable recursively saturated models of $\mathrm{PA}$, to results about the fixed point set of initial self-embeddings of countable nonstandard models of $\mathrm{I}\Sigma_{1}$.

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