**From:** J. Andrew Rogers (*andrew@ceruleansystems.com*)

**Date:** Fri May 21 2004 - 12:54:15 MDT

**Next message:**Eliezer Yudkowsky: "Re: ethics"**Previous message:**Giu1i0 Pri5c0: "Re: Dangers of human self-modification"**Maybe in reply to:**Phillip Huggan: "ethics"**Next in thread:**fudley: "Re: ethics"**Reply:**fudley: "Re: ethics"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ] [ attachment ]

John K Clark wrote:

*> I don’t know what you mean, I suppose you could have a machine that
*

*> always gives up after a fixed amount of time, but such a device would
*

*> hardly be “universal” and certainly doesn’t seem an appropriate
*

*> architecture for a super brain. Alan Turing proved 70 years ago that
*

*> sometimes you can’t even tell if you’re in a infinite loop or not.
*

I meant "universal" in the sense that all real computers are -- Finite

Turing Machines. UTMs are a mathematical amusement, and not relevant

here, particularly since even a "superbrain" probably won't have access

to one.

On a finite machine, it is quite possible to show that some specific

implementation will always halt. The Halting Problem is about *general*

solutions, not specific implementations. As I stated in my original

post, it is possible to have a computational model that is "universal"

but which can only approximate an infinite loop as a consequence of

being on a finite machine. Yes, if it was running on a genuine UTM the

Halting Problem would apply, but for finite machines you can prove that

it doesn't. In the pathological case it might return an approximation

to the correct answer when it runs out of space.

A finite machine that always halts has the caveat that while you will

always get some kind of answer, it will sometimes be an approximation of

the "correct" answer and sometimes not a very good approximation. But

that seems like a reasonable trade-off and an interesting way to exploit

finite state hardware.

j. andrew rogers

**Next message:**Eliezer Yudkowsky: "Re: ethics"**Previous message:**Giu1i0 Pri5c0: "Re: Dangers of human self-modification"**Maybe in reply to:**Phillip Huggan: "ethics"**Next in thread:**fudley: "Re: ethics"**Reply:**fudley: "Re: ethics"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ] [ attachment ]

*
This archive was generated by hypermail 2.1.5
: Wed Jul 17 2013 - 04:00:47 MDT
*