[FOM] Absolute undecidability

[Arne Hole]

Yes, you are right, I have fixed it now. Of course this is not a problem for the construction itself, since if $T_n$  proves its own inconsistency, then it does not have N as a model. 

Thanks, Arne. 


>Date: Wed, 3 Aug 2016 14:09:12 -0700
>From: Noah David Schweber <schweber at berkeley.edu>
>To: Foundations of Mathematics <fom at cs.nyu.edu>
>Subject: Re: [FOM] Absolute undecidability
>Message-ID:
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>mail.gmail.com>
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>Note that your $g_n$ is not always defined: if $T_n$ is consistent but proves
>its own inconsistency (e.g. if $A_n=~Con(PA)$) then $T_n$
>(vacuously) proves "If $T_n$ is consistent, then $B$ is undecidable in $T_n$"
>for **every** sentence $B$.
>
>On Wed, Aug 3, 2016 at 6:06 AM, Arne Hole <arne.hole at ils.uio.no> wrote:
>
>> I have once again updated my presentation concerning absolute
>> undecidability, and comments on the new version are very welcome. You
>> will find it on
>>
>> http://folk.uio.no/arnehole
>>
>> The presentation is a pdf of a PowerPoint, and it only takes a couple
>> of minutes to scan through. It is readable even on a smartphone screen.
>>
>> Best wishes, Arne H.