I tried this query some time ago here, without any success. Here it is
again, a bit more exactly:
(1) If I don't remember wrong, at least some time ago, Delta-1-2 CA (or
something like it) was the strongest theory which could be constructively
justified. Is this still the state of affairs?
(2) Now Finite Krusakal's Theorem (and extended KT, and such) are not
provable in predicatively justifiable theories, but are they still
provable in a theory that is constructively justifable?
(3) Are there any neat examples of theorems which are independent of
Delta-1-2 CA, or whatever theories which are, today, known to be
constructively acceptable?
(4) If there is, is the proof of independence itself constructive?
Best,
Panu
Panu Raatikainen
Ph.D., Academy Research Fellow,
Docent in Theoretical Philosophy
Department of Philosophy
University of Helsinki
Finland
E-mail: panu.raatikainen-pxSi+dnQzZMxHbG02/KK1g@xxxxxxxxxxxxxxxx
http://www.helsinki.fi/collegium/eng/Raatikainen/raatikainen.htm
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