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Article #1891

Re: Real Numbers vs. Rational Numbers?

#1891
From: Andrew Butterfield
Date: Wed, 06 Jan 1993 16:11
26 lines
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In article <1993Jan5.161955.11237@tom.rz.uni-passau.de>,
boerncke@kirk.fmi.uni-passau.de (Frank-Roland Boernke) wrote:
> 
> So what does this mean in the end? When I introduced this subject, I asked,
> whether a Turing Machine, that handles not only bits or naturals but also 
> real numbers is more powerful, than a turing machine, that only works 
> with natural numbers. 
> 
> My professor said, both types of Turing Machines are the same concerning
> their power of computability. I claimed that can't be true, refering to
> ideas  like the ones mentioned in the quotes at the beginning of this side.
> 
When you say "handles real numbers", do you mean that it can write real
numbers
into a single box on the tape ? If this is the case then your "R-Turing"
machine is different to a classic one, which has a potentially infinite
tape,
but only a finite set of symbols that it can write on the tape.

The R-Turing machine has an uncountably infinite set of symbols. It would
also need an uncountably infinite transition function to exploit the power
of its symbol set.

A classic Turing machine can "handle" real numbers in the same way as any
other computing devices, by working with finite approximations of those
real numbers.
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References: <1992Dec17.142150.7932@tom.rz.uni-passau.de> <1hi8dvINN5l2@uwm.edu> <1993Jan3.151347.29159@tom.rz.uni-passau.de> <4287@dozo.and.nl> <butrfeld-050193140552@butrfeld.cs.tcd.ie> <1993Jan5.161955.11237@tom.rz.uni-passau.de>

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From: butrfeld@cs.tcd.ie (Andrew Butterfield)
Subject: Re: Real Numbers vs. Rational Numbers?
Message-ID: <butrfeld-060193160334@butrfeld.cs.tcd.ie>
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References: <1992Dec17.142150.7932@tom.rz.uni-passau.de> <1hi8dvINN5l2@uwm.edu> <1993Jan3.151347.29159@tom.rz.uni-passau.de> <4287@dozo.and.nl> <butrfeld-050193140552@butrfeld.cs.tcd.ie> <1993Jan5.161955.11237@tom.rz.uni-passau.de>
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Date: Wed, 6 Jan 1993 16:11:53 GMT
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