Le 21-mai-06, à 10:53, Russell Standish a écrit :
>
> On Thu, May 18, 2006 at 11:38:24AM +0200, Bruno Marchal wrote:
>>>
>>> Also the universal dovetailer idea is also one of those that is
>>> fairly
>>> obvious, and might have been discovered a number of times
>>> independently.
>>
>>
>> I'm not sure it is so easy, and in the present case I have never heard
>> about some other papers.
>> Frankly I am not sure you got it right. I guess it is subtle: there is
>> a need of some amount in computer science to be astosnished that such
>> a
>> thing is logically possible. I will not develop this here because I
>> intend to make this clear in my reply (or sequence of replies) to Tom
>> and George.
>>
>
> I'm not sure why a knowledge of computer science would make the UD
> astonishing. If anything, I would have thought the opposite.
In a sense, you are obviously right. That is why I said "some"
knowledge of comp science or even just in math will make the existence
of the UD, and of the Universal Machine astonishing. Precisely it is
the knowledge of diagonalization. Godel will miss the universal machine
and Church thesis, and will describe those things as a sort of miracle.
More later. I will comment again with much more detail the rest of
your post much later. If I comment it here now I will introduce
confusion. It is preferable people get much more familiarity with the
effective and not effective daigonalisations procedures before, I
think.
> I'm
> interested to read your post to Tom and George.
Thanks for telling,
>
> The notion of dovetailing is really the theory behind timesharing, so
> simple dovetailing must be pretty obvious, at least since the early
> seventies.
>
> That one can dovetail on all possible programs must be pretty obvious
> once one realises that these can be enumerated. Of course the
> philosophial consequences of being able to do this is not so obvious,
> and as far as I know, you are the first person to have thought about
> that.
>
> Without the philosophical consequences, one would just think "so
> what?" So it is perhaps not surprising noone mentioned the UD before
> you.
>
>> Then I am showing that the appearances of "persons and realities" are
>> due to the incompleteness phenomena. I guess this is also a fairly
>> simple idea in the air, but, like the UD, I have not seen it develop
>> elsewhere, and it still gives me an hard and long time to make it
>> clear
>> as this very list can illustrate. And of course I can also be wrong,
>> also. My work mainly consists in making that idea testable (and
>> *partially* tested).
>>
>
> I sympathise, but I'm still having trouble getting the connection
> too. Nevertheless, I find it intriguing.
Which connection? Is it not utterly obvious that, IF we are (hopefully
reasonable) machine, THEN we will learn something genuine by studying
what (reasonable) machines can prove about themselves and about their
possible neighborhoods and or histories?
What is not obvious, is that computer science put strong constraints on
the nature of possible machine realities, and with comp a case is made
that all constraints comes from number theoretical relations
(intensional and extensional(*)) and associated measures.
And then the comp hyp is used just for making things easy. The only
fundamental assumption which is needed for the reversal physics/numbers
is the hypothesis of correct self-reference. But I don't want to
anticipate at this stage.
Bruno
(*) extensional: number represents themselves; intensional: number can
be used as code. Grosso modo: extensional number theory = "number
theory"; intensional number theory = computer science, information
science, provability logic.
http://iridia.ulb.ac.be/~marchal/
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Received on Tue May 23 2006 - 06:26:57 PDT