November 15
Roman Kossak, CUNY
Generalized quantifiers in arithmetic: Part II

This will be another talk in the MOPA series on the history of the subject.

The work on generalized quantifiers in formal systems of arithmetic was initiated in 1980 by Macintyre, motivated by the search for natural extensions of first-order arithmetic that are immune to the Kirby-Paris-Harrington style independence results. Some open questions posed by Macintyre were solved in a definitive way in 1982 by Schmerl and Simpson and after that Schmerl wrote two more papers on for Peano Arithmetic in the languages with Ramsay stationary quantifiers. Some results of Macintyre were obtained independently by Carl Morgenstern. All these papers, while very well written, are quite technical and not easily accessible for readers who are not familiar with more advanced tools of the model theory of arithmetic. I will survey the results suppressing most technical details. I will also talk about an attempt to use logic with stationary quantifiers to classify $\omega_1$-like recursively saturated models of PA.