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Path: ...!eternal-september.org!feeder3.eternal-september.org!news.szaf.org!news.karotte.org!news.space.net!news.muc.de!.POSTED.news.muc.de!not-for-mail From: Alan Mackenzie <acm@muc.de> Newsgroups: sci.math Subject: Re: How many different unit fractions are lessorequal than all unit fractions? (infinitary) Date: Sat, 19 Oct 2024 20:19:34 -0000 (UTC) Organization: muc.de e.V. Message-ID: <vf148m$o0d$1@news.muc.de> References: <vb4rde$22fb4$2@solani.org> <2b6f9104-a927-49ee-9cf0-6ee3f82edc23@att.net> <verkkk$2r6kk$1@dont-email.me> <verlk6$4dv$1@news.muc.de> <vermdv$2s24h$1@dont-email.me> <verv6f$2oo0$1@news.muc.de> <e4d00f83-42df-4f14-a007-4a90f3b5d644@tha.de> <vf085m$1gf6$1@news.muc.de> <vf0cpf$3t4q1$1@dont-email.me> <vf0feo$2un7$1@news.muc.de> <vf0ovc$3v3cv$1@dont-email.me> <vf0qev$2fe9$1@news.muc.de> <47ada01f-e2a7-42e7-bb63-390a73412938@tha.de> <vf0tdu$2fe9$2@news.muc.de> <vf0vo9$6c6$2@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Injection-Date: Sat, 19 Oct 2024 20:19:34 -0000 (UTC) Injection-Info: news.muc.de; posting-host="news.muc.de:2001:608:1000::2"; logging-data="24589"; mail-complaints-to="news-admin@muc.de" User-Agent: tin/2.6.3-20231224 ("Banff") (FreeBSD/14.1-RELEASE-p3 (amd64)) Bytes: 2504 Lines: 33 WM <wolfgang.mueckenheim@tha.de> wrote: > On 19.10.2024 20:22, Alan Mackenzie wrote: >> WM <wolfgang.mueckenheim@tha.de> wrote: >> An infinite set is one which has a proper subset which can be >> put into 1-1 correspondence with the original set. That is the >> definition. > According to Dedekind every set {1, 2, 3, ..., n} is in correspondence=20 > with the set {2, 4, 6, ..., 2n} which covers twice the interval,=20 > containing numbers not in the original set. This is true, though has nothing to do with my point about the definition of an infinite set. > This does not change when the whole set =E2=84=95 is multiplied by 2. It does. It changes dramatically. > The result covers twice the interval, .... It does not, except in the sense that twice infinite =3D infinite. > .... containing numbers not in the original set =E2=84=95. No. If you think that, then give an example of a 2n which "isn't in the original set N". You won't and you can't. But you'll likely come back to your standard get-out clause about (non existent) "dark numbers". > Regards, WM --=20 Alan Mackenzie (Nuremberg, Germany).