[FOM] Equivalence relation on sets of natural numbers

Robert Black mongre at gmx.de
Tue Sep 11 13:51:21 EDT 2012

I don't know about names of the relation or the equivalence classes, but 
the *abstraction principle* corresponding to this equivalence relation 
(on the power set of any set, not just N) gets discussed in neo-Fregean 
circles, since it is satisfiable only in finite domains, whereas 'Hume's 
principle' is satisfied only in infinite domains. If I remember 
correctly, Crispin Wright called it the 'nuisance principle' because it 
was a nuisance for neo-Fregeans.


Am 11.09.12 16:37, schrieb Timothy Y. Chow:
> I want to declare that two sets of natural numbers are equivalent if 
> their symmetric difference is finite.
> Is there a standard term for the resulting family of equivalence 
> classes, or for the equivalence relation?  I feel like I've seen this 
> somewhere before but I can't recall where.
> Tim
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