Re: Incorrect requirements --- Computing the mapping from the input to HHH(DD)

On 12/05/2025 01:38, Mike Terry wrote:

On 11/05/2025 18:11, Richard Heathfield wrote:

On 11/05/2025 17:44, olcott wrote:

Any yes/no question where both yes and no are the
wrong answer is an incorrect polar question.

>
Either DD stops or it doesn't (once it's been hacked around to get it to compile and after we've leeched out all the dodgy programming).

 Done that.

And you still had code left?

It still stops.

Okay.

If the computer cannot correctly decide whether or not DD halts,

 The decider says it doesn't stop..

I said "cannot >>>correctly<<< decide".

 

we have an undecidable computation,

 No no, that doesn't make sense.

Agreed. Therefore, even *after* taking out all the dodgy code, the decider must be broken.

 DD stops, and there are lots of partial halt deciders that will decide that particular input correctly.  PO's DD isn't "undecidable".

I hear what you're saying (or at least I see what you typed), but if DD's result is so decidable, how come his decider can't correctly decide?

No single computation can be undecidable, considered on its own!  There are only two possibilities: it halts or it doesn't.

Or both, it seems. You say it halts (and I would not hesitate to take you at your word if the alternative is to dredge up a Windows system from somewhere). Olcott says it is non-halting.
And we both know it /can't/ be both...
--
Richard Heathfield
Email: rjh at cpax dot org dot uk
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