Article View: comp.theory
Article #1881Re: Real Numbers vs. Rational Numbers?
From: Frank-Roland Boernke
Date: Tue, 05 Jan 1993 16:19
Date: Tue, 05 Jan 1993 16:19
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2587 bytes
In article <butrfeld-050193140552@butrfeld.cs.tcd.ie>, butrfeld@cs.tcd.ie (Andrew Butterfield) writes: |> In article <4287@dozo.and.nl>, jos@and.nl (Jos Horsmeier) wrote: |> > |> > In article <1993Jan3.151347.29159@tom.rz.uni-passau.de> boerncke@kirk.fmi.uni-passau.de (Frank-Roland Boernke) writes: |> > |> > |For 2/5 you can find a finite numeric representation ( 0.4 ) |> > |for PI or PI*PI you cannot! |> > |> > But what if we use a base PI representation? PI*PI obviously equals 100, |> > which is definitely a finite numeric representation. There is none for 2/5, |> > when using base PI. |> > |> > kind regards and happy new year! |> > |> > Jos aka jos@and.nl |> |> |> You cannot represent 1, 2, 3, exactly either --- "base PI" doesn't seem |> much use. |> |> Say we have 12 and 23 as numbers in your base PI, how do we add them ? |> What gets carried and how is it represented ? |> |> The key point is that no matter what base you choose, it will not be |> capable of |> giving a finite representation to all real numbers. Real numbers are |> inherently |> infinite objects. |> 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. Who is right? ------------------------------------------------------------------------- Frank Boerncke ,,, University of Passau - Germany boerncke@kirk.fmi.uni-passau.de (.~.) phone: +49 0851 2267 --------------------------------oOO--(_)--OOo---------------------------
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Newsgroups: comp.theory Path: arc1-ca.pugleaf.net!sparky!uunet!math.fu-berlin.de!informatik.tu-muenchen.de!rz.uni-passau.de!kirk.fmi.uni-passau.de!boerncke From: boerncke@kirk.fmi.uni-passau.de (Frank-Roland Boernke) Subject: Re: Real Numbers vs. Rational Numbers? Message-ID: <1993Jan5.161955.11237@tom.rz.uni-passau.de> Sender: news@tom.rz.uni-passau.de (News-Operator) Organization: University of Passau, Germany 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> Distribution: inet Date: Tue, 5 Jan 1993 16:19:55 GMT Lines: 49