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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: bart again (UCX64)
Date: Wed, 06 Sep 2023 08:47:59 -0700
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Kaz Kylheku <864-117-4973@kylheku.com> writes:

> On 2023-09-05, Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>
>> Kaz Kylheku <864-117-4973@kylheku.com> writes:
>>
>>> A Turing machine is completely defined and has no run-time inputs;
>>> everything is on the tape.
>>
>> This is wrong.  A Turing machine is just the machine.  The tape is
>> separate.
>
> Apologies for that.  A term for what I'm referring to is
> "Turing machine configuration" (offered in _Introduction to the
> Theory of Computation_, 3rd ed, Michael Sipser).

Not a term I'm familiar with.  Seems like a poor choice
of phrase.

>> It would be pointless to talk about "Turing machines"
>> if all a given "Turing machine" could do is one computation.
>
> "Does this Turing machine configuration halt?" is a
> meaningful question.

The question usually asked is "Does a given Turing machine halt
when started on a blank tape?".  Given a Turing machine T and
input tape I, it's easy to construct a Turing machine T' such
that T' halts when started on a blank tape if and only iff T
halts when started on I.  ISTM that the notion of a Turing
machine configuration (whether by that name or a different one)
isn't very useful.