Cuts in models of PA and independence results

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Diversity in elementary cuts

Let MPA be countable and recursively saturated.

Smorybski proved that here are 20 theories of pairs (M,K), such that K is not semiregular in M.

Kossak proved that there are 20 theories of pairs (M,K), such that K is strong in M.

Problem: How many theories of pairs (M,K) are there, such that K is semiregular, but not regular in M.

By recent results of Kaye and Tin Lok Wong, every countable recursively saturated M has K and L as in the question, such that (M,K)(M,L).


References:

Smoryński, C. Elementary extensions of recursively saturated models of arithmetic. Notre Dame J. Formal Logic 22 (1981), no. 3, 193–203.

Smoryński, C. A note on initial segment constructions in recursively saturated models of arithmetic. Notre Dame J. Formal Logic 23 (1982), no. 4, 393–408

Kossak, Roman A note on satisfaction classes. Notre Dame J. Formal Logic 26 (1985), no. 1, 1–8.

Kaye, Richard; Wong, Tin Lok Truth in generic cuts. Ann. Pure Appl. Logic 161 (2010), no. 8, 987–1005.