[FOM] Synonymity

[praatika@mappi.helsinki.fi]

Dear Alasdair

Thank you very much for your message. 

Alasdair Urquhart <urquhart at cs.toronto.edu> wrote:

> I have a vague recollection that first order
> Peano Arithmetic is synonymous with ZF + the
> negation of the axiom of infinity.  Is that
> right?

This is exactly the kind of case I would like to have, and I feel that many 
assume they are something like synonmous, but I've never seen it explicitly 
stated (in the meager literature on synonymity), not to mention proved. On 
the other hand, I have some doubts that they may after all turn out to be 
non-synonymous...
I hoped that someone knew for sure. Maybe I sould just try to check it 
myself...  

* * *

Your paper "Synonymous Logics" seems very interesting. Unfortunately I have 
now some problems with my new Latex version... I wonder if you  could send 
a .dvi, .ps or .pdf version - if that is not too much trouble? 

All the Best

Panu

Panu Raatikainen

PhD., Docent in Theoretical Philosophy
Fellow, Helsinki Collegium for Advanced Studies
University of Helsinki

Address: 
Helsinki Collegium for Advanced Studies
P.O. Box 4
FIN-00014 University of Helsinki
Finland

E-mail: panu.raatikainen at helsinki.fi

http://www.helsinki.fi/collegium/eng/Raatikainen/raatikainen.htm