[FOM] Relevance of reverse mathematics to constructivity

Daniel Méhkeri dmehkeri at yahoo.ca
Sun Mar 28 13:02:46 EDT 2010

> If you don't mind, please do fill in a bit. Specifically, if one can 
> safely lose the witness, why isn't AC_{00} valid?

When I said that the difference between primitive N and set-theoretic
omega wasn't important, I really meant to say countable choice (even dependent choices) would be _valid_ in both contexts.

In fact dependent choices might even be the easier one to see, because the
hypothesis would basically be the same. Use dependent choices over N,
then find a way to encode the result as a countable subset of omega times x.



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