[FOM] strong arithmetical theorems?

Panu Raatikainen panu.raatikainen at helsinki.fi
Sun Oct 17 14:34:21 EDT 2010

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.

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

E-mail: panu.raatikainen at helsinki.fi

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