**MW:** Last time we learned about the “back-and-forth” condition for two countable structures *M* and *N* for a (countable) language *L*:

# Monthly Archives: April 2023

## Nonstandard Models of Arithmetic 31

Filed under Conversations, Peano Arithmetic

## Nonstandard Models of Arithmetic 30

**MW:** Time to finish off Enayat’s Theorem 7:

**Theorem 7:** Every countable recursively saturated model *N* of PA+Φ* _{T}* is a

*T*-standard model of PA.

Filed under Conversations, Peano Arithmetic

## Nonstandard Models of Arithmetic 29

**MW:** We’re still going through Enayat’s proof of his Theorem 7:

**Theorem 7:** Every countable recursively saturated model *N* of PA+Φ* _{T}* is a

*T*-standard model of PA.

Filed under Conversations, Peano Arithmetic