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Date: Tue, 12 Apr 2011 11:44:19 -0700
Subject: Re: Free software versus software idea patents
From: Dan Stromberg <drsalists@gmail.com>
To: Terry Reedy <tjreedy@udel.edu>
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:3076

On Tue, Apr 12, 2011 at 10:32 AM, Terry Reedy <tjreedy@udel.edu> wrote:
> On 4/11/2011 4:36 AM, rusi wrote:
>
>> http://www.cse.uconn.edu/~dqg/papers/cie05.pdf
>>
>> may be of interest (and also other papers of Peter Wegner questioning
>> the universality of Turing machines lambda calculus etc)
>
> Thank you for that reference. In summary, it says that while Turing machine
> are universal for finite function calculations, infinite interactive
> processes are not (finite) function calculations, and therefore need an
> extension to TMs. This is pretty obviously correct.
>
> Python iterators, and especially generators, implement the extension that
> the authors call 'persistent Turing machines' (PTMs, section 6.2), except
> that iterators (and generators by default) operate in 'pull' mode, while
> they describe PTMs as operating in 'push' mode (as with generator.send()).

I didn't read the paper, but I believe Turing Machines are infinite.

Interactive processes don't seem, at least to me, to change the
applicability of Turing Machines - you merely pretend you have a bunch
of squares preinitialized with your various inputs.  If you have an
infinite number of inputs, that's fine, you can have them with a
preinitialized turing machine.