Re: Arthur O'Dwyer on the feasibility of simulating a Turing Machine

From: Richard Heathfield (dontmail_at_address.co.uk.invalid)
Date: 02/29/04 

Date: Sun, 29 Feb 2004 11:30:45 +0000 (UTC)

Michael Mendelsohn wrote:

> "Edward G. Nilges" schrieb:

<snip>

>
>> We can see pace Ian that most special purpose Turing Machines can be
>> simulated as long as their computation and tape is bounded, and known
>> to be so.
>
> I do not understand what "pace" means.

Latin: commonly pronounced "par-chay", derived from the Latin for peace,
"pax". It literally means "be at peace", or something along those lines. In
normal usage, one would say "pace X" to mean, "yes, X, I know you have an
issue with what I'm about to say (or have just said), but bear with me for
now".

That was from memory. I now turn to my dictionary, which says:

"pace [pron guides elided] with or by the leave of (expressing disagreement
courteously). [L. ablative of /pax/ peace]"

Well, I wasn't far off, was I? :-)

The pronunciations the dictionary suggests could perhaps be written in a
typographically poor environment like this one as: par-say, par-kay,
par-chay. Accent on first syllable.

Of course, what Nilges was actually saying is pure hogwash. Using the word
"most" in connection with Turing Machines, for example, is meaningless,
since there are infinitely many special purpose Turing Machines with
bounded computation and tape but which cannot be simulated. A single
example should suffice: solve TSP by brute force, where the nodes are all
the electrons in the universe, in their positions as at 12 noon GMT on 29
February 2004 AD. (This example *on its own* can of course spawn infinitely
many similar examples.)

<snip> 

-- 
Richard Heathfield : binary@eton.powernet.co.uk
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