Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: FromTheRafters Newsgroups: sci.math Subject: Re: Incompleteness of Cantor's enumeration of the rational numbers (extra-ordinary) Date: Wed, 04 Dec 2024 05:29:28 -0500 Organization: Peripheral Visions Lines: 48 Message-ID: References: <71758f338eb239b7419418f49dfd8177c59d778b@i2pn2.org> <87frn50zjp.fsf@bsb.me.uk> Reply-To: erratic.howard@gmail.com MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15"; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 04 Dec 2024 11:29:35 +0100 (CET) Injection-Info: dont-email.me; posting-host="36d1760a1ed0cb3157bb9bb0b6985926"; logging-data="865403"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19K42MJlI/7V+HAUhvIIDFUoB9y8UKO5Yc=" Cancel-Lock: sha1:KRczJQ//qQ5Nswf5cJJB4srI37k= X-Newsreader: MesNews/1.08.06.00-gb X-ICQ: 1701145376 Bytes: 3398 Moebius expressed precisely : > Am 04.12.2024 um 02:02 schrieb Moebius: >> Am 04.12.2024 um 01:47 schrieb Chris M. Thomasson: >>> On 12/3/2024 2:32 PM, Moebius wrote: >>>> Am 03.12.2024 um 23:16 schrieb Moebius: >>>>> Am 03.12.2024 um 22:59 schrieb Chris M. Thomasson: >>>> >>>>>> However, there is no largest natural number, when I think of that I see >>>>>> no limit to the naturals. >>>> >>>> Right. No "coventional" limit. Actually, >>>> >>>>       "lim_(n->oo) n" >>>> >>>> does not exist. >>> >>> In the sense of as n tends to infinity there is no limit that can be >>> reached [...]? >> >> Exactly. >> >> We say, n is "growing beyond all bounds". :-P > > On the other hand, if we focus on the fact that the natural numbers are sets > _in the context of set theory_, namely > > 0 = {}, 1 = {{}}, 2 = {{}, {{}}, ... Typo, needs another closing curly bracket. > => 0 = {}, 1 = {0}, 2 = {0, 1}, ... > > (due to von Neumann) > > then we may conisider the "set-theoretic limit" of the sequence > > (0, 1, 2, ...) = ({}, {0}, {0, 1}, ...). > > This way we get: > > LIM_(n->oo) n = {0, 1, 2, ...} = IN. :-P > > I'd like to mention that "lim_(n->oo) n" is "old math" (oldies but goldies) > while "LIM_(n->oo) n" is "new math" (only possible after the invention of set > theory (->Cantor) and later developments (->axiomatic set theory, natural > numbers due to von Neumann, etc.). If you say so, but I haven't seen this written anywhere.