[FOM] strong arithmetical theorems?

[Panu Raatikainen]

Correction: not EFA - it was supposed to be I\Delta_0+\Omega_1...   
(thanks to Richard Heck for pointing this out). Sorry!

The real issue being: theories interpretable in Q.
-Panu

I wrote:

> Are there natural theorems of ordinary *arithmetic* which are not
> provable in weak theories such as S^1_2, EFA and such (that is,
> theories that can be interpreted in the Robinson Arithmetic Q) but
> require at least RCA_0, or something ?



-- 
Panu Raatikainen

Ph.D., Docent in Theoretical Philosophy

Department of Philosophy, History, Culture and Art Studies
P.O. Box 24  (Unioninkatu 38 A)
FIN-00014 University of Helsinki
Finland

E-mail: panu.raatikainen at helsinki.fi
http://www.mv.helsinki.fi/home/praatika/