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g_pepper comments on Open thread, Feb. 23 - Mar. 1, 2015 - Less Wrong Discussion

3 Post author: MrMind 23 February 2015 08:01AM

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Comment author: g_pepper 26 February 2015 05:05:19PM 2 points [-]

I don't think I know a human who would have a zero error rate doing 1,000,000,000 Turing operations

Nor do I. However, this is irrelevant. In determining whether a system is Turing complete, physical limitations are usually ignored. From Wikipedia:

To show that something is Turing complete, it is enough to show that it can be used to simulate some Turing complete system. For example, an imperative language is Turing complete if it has conditional branching (e.g., "if" and "goto" statements, or a "branch if zero" instruction. See OISC) and the ability to change an arbitrary amount of memory locations (e.g., the ability to maintain an arbitrary number of variables). Since this is almost always the case, most (if not all) imperative languages are Turing complete if the limitations of finite memory are ignored.

If we did not ignore physical limitations, no actual computing system would be Turing complete.

Comment author: ChristianKl 26 February 2015 05:07:10PM -1 points [-]

Making errors means not behaving as a Turing machine. It's separate from limitations of memory.

Comment author: Lumifer 26 February 2015 05:11:59PM 2 points [-]

Any physical Turing machine will make errors.

Comment author: ChristianKl 26 February 2015 05:13:35PM -1 points [-]

To the extend that it does it's no ideal Turing machine.

Comment author: Lumifer 26 February 2015 05:15:03PM 3 points [-]

Ideal Turing machines, being, y'know, ideal, do not exist in reality.

Comment author: ChristianKl 26 February 2015 05:16:31PM -1 points [-]

It's a model. Models have it's use. It makes sense to model a computer as an ideal Turing machine. It doesn't make much sense to model a human that way.

Comment author: Lumifer 26 February 2015 05:22:38PM 4 points [-]

Nobody suggested modeling humans as Turing machines. The question was whether humans are Turing complete and you implied that they are not because they make errors. By the same standard, no physical device is Turing complete.

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