[FOM] Deflationism and the Godel phenomena

Harvey Friedman friedman at math.ohio-state.edu
Tue Feb 15 20:45:17 EST 2005

On 2/15/05 4:30 PM, "Jeffrey Ketland" <ketland at ketland.fsnet.co.uk> wrote:

> Right. I noted that Tr(PA) is equivalent to ACA.

What does the word "equivalent" mean here?
What does "Tr(PA)" mean here?

ACA normally refers to the two sorted system of arithmetic comprehension
with parameters and full induction.

Harvey Friedman 

More information about the FOM mailing list