paper-machine comments on Bounded versions of Gödel's and Löb's theorems - Less Wrong

32 Post author: cousin_it 27 June 2012 06:28PM

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Comment author: [deleted] 27 June 2012 07:53:21PM *  4 points [-]

When I get some time I'll sit down and read these more carefully. However, before that time comes I wanted to congratulate you on tackling these things!

<3

EDIT 1: Remarks on Bounded Goedel's theorem

1) It is unclear (to me, who has not studied such things in several years) where the proof uses the fact that T includes PA. Maybe it is necessary for the construction of R?

Other than that, I rewrote the proof as explicitly as I could (supplying some missing details and the like) and found no issues.

Comment author: cousin_it 28 June 2012 07:07:58AM *  2 points [-]

Thanks!

It is unclear (to me, who has not studied such things in several years) where the proof uses the fact that T includes PA. Maybe it is necessary for the construction of R?

Saying that T includes PA is shorthand for the usual Gödelian requirement that T includes the basic arithmetical truths necessary to formalize the bits of common-sense reasoning used in the proof, like simulating the execution of R.

Comment author: [deleted] 28 June 2012 08:11:20AM 2 points [-]

I figured as much; after all, in the standard proof one only needs PA around long enough to construct Goedel numbers.