Path: ...!weretis.net!feeder9.news.weretis.net!news.quux.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Moebius Newsgroups: sci.math Subject: Re: Incompleteness of Cantor's enumeration of the rational numbers (extra-ordinary) Date: Wed, 4 Dec 2024 08:47:45 +0100 Organization: A noiseless patient Spider Lines: 45 Message-ID: References: <71758f338eb239b7419418f49dfd8177c59d778b@i2pn2.org> <87frn50zjp.fsf@bsb.me.uk> Reply-To: invalid@example.invalid MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 04 Dec 2024 08:47:45 +0100 (CET) Injection-Info: dont-email.me; posting-host="f54805dd0852139be813890d7a58bd55"; logging-data="780187"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+x5AMEj6lGF10eNNWbsBF/" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:bVBs6NLBJ2WotBiB/zcls9VPpm8= In-Reply-To: Content-Language: de-DE Bytes: 3293 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 = {{}, {{}}, ... => 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.).