Path: ...!eternal-september.org!feeder2.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 Date: Sat, 23 Nov 2024 06:32:09 +0100 Organization: A noiseless patient Spider Lines: 28 Message-ID: References: <094dadad718eaa3827ad225d54aaa45b880dd821@i2pn2.org> <3399a95e386bc5864f1cfcfc9f91f48366e0fed2@i2pn2.org> <0d551828411c0588000796fa107a16b1e23a866c@i2pn2.org> <74bdc0f14fd0f2c6bfd9ac511a37f66b41948ac4@i2pn2.org> Reply-To: invalid@example.invalid MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Sat, 23 Nov 2024 06:32:09 +0100 (CET) Injection-Info: dont-email.me; posting-host="27740ff8e43fcfb22f5893043c471488"; logging-data="1679110"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+gNVIwJdzkbVHWv6gaPLZ6" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:50vyiVXExxz04X2IpSuGgo+qvEk= In-Reply-To: Content-Language: de-DE Bytes: 2813 Am 23.11.2024 um 06:18 schrieb Moebius: >>> On 22.11.2024 16:11, joes wrote: >>>> Am Fri, 22 Nov 2024 15:51:11 +0100 schrieb WM: > >>>>> the sets of naturals and of prime numbers [can] cover each other. >>>>> >>>> As it should. You can give each prime an index. > > Indeed! The two formulas > > | p(1) = min P > | p(n+1) = min {p e P : p > p(n)}   (for all n e IN) > > (recursively) define the function p: IN --> P. Where IN is the set of > all natural numbers and P is the set of all prime numbers. > > Hint: p(1) = 2, p(2) = 3, p(3) = 5, ... > > Actually, if p e P, then there is an (index) n e IN such that p(n) = p. > > (It's easy to prove that p: IN --> P is a bijection.) p(n) is the n-th prime number in the sequence of prime numbers ordered by size. .. .. ..