Path: ...!weretis.net!feeder9.news.weretis.net!news.nk.ca!rocksolid2!i2pn2.org!.POSTED!not-for-mail From: joes Newsgroups: sci.math Subject: Re: Incompleteness of Cantor's enumeration of the rational numbers Date: Tue, 19 Nov 2024 16:27:52 -0000 (UTC) Organization: i2pn2 (i2pn.org) Message-ID: <094dadad718eaa3827ad225d54aaa45b880dd821@i2pn2.org> References: <157a949d-6c19-4693-8cee-9e067268ae45@att.net> <8165b44b-1ba5-429d-8317-0b043b214b53@att.net> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Tue, 19 Nov 2024 16:27:52 -0000 (UTC) Injection-Info: i2pn2.org; logging-data="3184812"; mail-complaints-to="usenet@i2pn2.org"; posting-account="nS1KMHaUuWOnF/ukOJzx6Ssd8y16q9UPs1GZ+I3D0CM"; User-Agent: Pan/0.145 (Duplicitous mercenary valetism; d7e168a git.gnome.org/pan2) X-Spam-Checker-Version: SpamAssassin 4.0.0 Bytes: 3827 Lines: 49 Am Tue, 19 Nov 2024 16:24:52 +0100 schrieb WM: > On 18.11.2024 23:40, FromTheRafters wrote: >> WM wrote on 11/18/2024 : >>> On 18.11.2024 22:58, FromTheRafters wrote: >>>> on 11/18/2024, WM supposed : >>>>> On 18.11.2024 18:15, FromTheRafters wrote: >>>>>> WM brought next idea : >>>>> >>>>>>>> |ℕ| - |ℕ| = 0 because if you subtract one element from ℕ then you >>>>>>>> have no longer ℕ and therefore no longer |ℕ| describing it. >>>>> If you remove one element from ℕ, then you have still ℵo but no >>>>> longer all elements of ℕ. >>>> But you do have now a proper subset of the naturals the same size as >>>> before. >>> It has one element less, hence the "size" ℵo is a very unsharp >>> measure. >> Comparing the size of sets by bijection. Bijection of finite sets give >> you a same number of elements, bijection of infinite sets give you same >> size of set. > Why? Because only potential infinity is involved. True bijections pr5ove > equinumerosity. What is a "true" bijection? >>>>> If |ℕ| describes the number of elements, then it has changed to |ℕ| >>>>> - 1. >>>> Minus one is not defined. >>> Subtracting an element is defined. |ℕ| - 1 is defined as the number of >>> elements minus 1. >> Nope! > The number of ℕ \ {1} is 1 less than ℕ. And what, pray tell, is Aleph_0 - 1 ? >>>>> If you don't like |ℕ| then call this number the number of natural >>>>> numbers. >>>> Why would I do that when it is the *SIZE* of the smallest infinite >>>> set. >>> The set of prime numbers is smaller. >> No, it is not. > It is, because 4 and 8 are missing. It is a subset. > > There is a bijection. > Only between numbers which have more successors than predecessors, All of them do. > although it is claimed that no successors are remaining. -- Am Sat, 20 Jul 2024 12:35:31 +0000 schrieb WM in sci.math: It is not guaranteed that n+1 exists for every n.