Quentin Anciaux-2 wrote:
> 
> 2012/9/11 benjayk <benjamin.jaku...@googlemail.com>
> 
>>
>>
>> Quentin Anciaux-2 wrote:
>> >
>> > 2012/9/11 benjayk <benjamin.jaku...@googlemail.com>
>> >
>> >>
>> >>
>> >> Quentin Anciaux-2 wrote:
>> >> >
>> >> > 2012/9/10 benjayk <benjamin.jaku...@googlemail.com>
>> >> >
>> >> >>
>> >> >>
>> >> >> > > No program can determine its hardware.  This is a consequence
>> of
>> >> the
>> >> >> > > Church
>> >> >> > > Turing thesis.  The particular machine at the lowest level has
>> no
>> >> >> > bearing
>> >> >> > > (from the program's perspective).
>> >> >> > If that is true, we can show that CT must be false, because we
>> *can*
>> >> >> > define
>> >> >> > a "meta-program" that has access to (part of) its own hardware
>> >> (which
>> >> >> > still
>> >> >> > is intuitively computable - we can even implement it on a
>> computer).
>> >> >> >
>> >> >>
>> >> >> It's false, the program *can't* know that the hardware it has
>> access
>> >> to
>> >> >> is
>> >> >> the *real* hardware and not a simulated hardware. The program has
>> only
>> >> >> access to hardware through IO, and it can't tell (as never ever)
>> from
>> >> >> that
>> >> >> interface if what's outside is the *real* outside or simulated
>> >> outside.
>> >> >> <\quote>
>> >> >> Yes that is true. If anything it is true because the hardware is
>> not
>> >> even
>> >> >> clearly determined at the base level (quantum uncertainty).
>> >> >> I should have expressed myself more accurately and written "
>> >> "hardware"
>> >> "
>> >> >> or
>> >> >> "relative 'hardware'". We can define a (meta-)programs that have
>> >> access
>> >> >> to
>> >> >> their "hardware" in the sense of knowing what they are running on
>> >> >> relative
>> >> >> to some notion of "hardware". They cannot be emulated using
>> universal
>> >> >> turing
>> >> >> machines
>> >> >
>> >> >
>> >> > Then it's not a program if it can't run on a universal turing
>> machine.
>> >> >
>> >> The funny thing is, it *can* run on a universal turing machine. Just
>> that
>> >> it
>> >> may lose relative correctness if we do that.
>> >
>> >
>> > Then you must be wrong... I don't understand your point. If it's a
>> program
>> > it has access to the "outside" through IO, hence it is impossible for a
>> > program to differentiate "real" outside from simulated outside... It's
>> a
>> > simple fact, so either you're wrong or what you're describing is not a
>> > program, not an algorithm and not a computation.
>> OK, it depends on what you mean by "program". If you presume that a
>> program
>> can't access its "hardware",
> 
> 
> I *do not presume it*... it's a *fact*.
> 
> 
Well, I presented a model of a program that can do that (on some level, not
on the level of physical hardware), and is a program in the most fundamental
way (doing step-by-step execution of instructions).
All you need is a program hierarchy where some programs have access to
programs that are below them in the hierarchy (which are the "hardware"
though not the *hardware*).

So apparently it is not so much a fact about programs in a common sense way,
but about a narrow conception of what programs can be.

benjayk
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