[PD] Pd *is* a programming language!

[padawan12]

http://plato.stanford.edu/entries/church-turing/

The Church-Turing thesis is quite misunderstood actually.
Issues of computability are fascinating and build on
the work of Godel, Kleene, Russell, Hilbert, Church and Turing.

Daniel Dennet and Douglas Hoffstadter present some 
famously accesible laymans analysis of it. 

Church used predicate calculus, and Turing a mechanical
analogy. In a limited sense they are equivilent, but there
are subtleties and several versions of the thesis which differ
in strength. A universal computer and a universal Turing
machine are not the same thing, that is to say anything
that is Turing computable can be computed on any Turing
machine (like a modern Von Neumann computer) but that isn't
the same as saying it can compute "anything". Getting Godel
helps with this - not all things are computable by a finite
symbolic logic, that doesn't mean they are not computable at all.

In a modern context the thesis seems quite unremarkable since
any pocket calculator is essentialy "Turing complete" and we
are so used to computing machines we take it for granted
that you can run BSD on a toaster. But it has profound philosophical
implications. Contrast Penfield with Churchland if you want to
grapple this issue vis determinism and computability.
The contoversy is still powerful in AI research on the equivilence
of neural and finite state computing.

Yes, you could implement Linux in Pd.
And you could implement Linux running a VM running Pd implementing
Linux... if you had the time and some peverse reason to try.

No you could not implement the "internet" in Pd because
the internet is not a program, it is a distributed data store.




On Fri, 29 Sep 2006 15:06:51 -0400
"Chuckk Hubbard" <badmuthahubbard at gmail.com> wrote:

> I read two Wikipedia articles, and I still have no idea what this means.
> One could conceivably run Linux under Pd?  Or the internet?  wild.
> 
> On 9/28/06, Claude Heiland-Allen <claudiusmaximus at goto10.org> wrote:
> > Hi everybody,
> >
> > Remember those long discussions about whether Pd is a programming
> > language or (an inferior) something else?
> >
> > Well, to settle the matter, I made a brainf*ck[1] interpreter in vanilla
> > Pd using no externals[2].
> >
> > Now you can be sure that you can compute anything computable[3] using
> > your favourite multimedia tool!
> >
> > As Pd's string handling sucks, output is a printout of the decimal value
> > of each character.
> >
> > Keyboard input is through [key], so you enter characters fairly
> > naturally (wait for the yellow signal before you type each character).
> > There is no way to indicate end-of-file.
> >
> >
> > [1] http://en.wikipedia.org/wiki/Brainfuck
> >
> > [2] As Pd's string handling sucks, you need to convert your .bf source
> > code into decimal form before loading it.  A simple C program
> > "decdump.c" to do this is attached.
> >
> > [3] Provided it can be computed within the memory available, which in
> > this interpreter is 1,000,000 cells each being an integer from 0 to 255
> > inclusive.
> >
> >
> > Claude
> 
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