Virgil
Posts:
4,482
Registered:
1/6/11
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Re: Objection to Cantor's First Proof
Posted:
Jul 31, 2012 10:56 PM
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In article <cef3510f-6eca-4e42-9bbe-341b3aa31e0a@id7g2000pbc.googlegroups.com>, "Ross A. Finlayson" <ross.finlayson@gmail.com> wrote:
> On Jul 31, 12:48 pm, Virgil <vir...@ligriv.com> wrote: > > In article <jv8mt2$ok...@speranza.aioe.org>, > > > > "LudovicoVan" <ju...@diegidio.name> wrote: > > > > I'll state the main point again: my counter-argument works either with > > > > an > > > > enumeration from N to R (supposedly, the original Cantorian setting), > > > > or > > > > with an enumeration from N* to R*. The reason why Cantor's First Proof > > > > fails is because of invalid reasoning with putative sequences from N to > > > > R* > > > > (so that an a_oo looks like it is missing from the enumeration). > > > > > That's wrongly put: the point just boils down to the fact that, to > > > consider > > > a_oo as a real number that belongs or does not belong to (x_n), we need > > > consider sequences over N*. > > > > You may need to but those who are basing their analysis on standard > > mathematics do not. > > > > It is well known in standard mathematics that a nested sequence of real > > intervals, with each being a proper subinterval of all its predecessors, > > has a non-empty intersection, which may be an interval of positive > > length, in which case your alleged a_oo is a real an interval of > > positive length. > > -- > > > > > > > Huh, well how exactly the opposite that is to what you wrote before. > Actually not at all different from what wrote before. But what I wrote seems to be quite different from what you claim to have read. --
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