Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: WM Newsgroups: sci.math Subject: Re: The set of necessary FISONs Date: Mon, 3 Mar 2025 10:20:20 +0100 Organization: A noiseless patient Spider Lines: 24 Message-ID: References: <067f772a-4f4c-4c27-8042-3f605f814876@att.net> <4bce9826fcd4c68b4785aabc83de9394eae61402@i2pn2.org> <2a62cfa0db610ef9bb26903f8e9417e96e1bfa57@i2pn2.org> <4a9f36181152eb4df4a819f7abcdaae5de1f3d09@i2pn2.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Mon, 03 Mar 2025 10:20:20 +0100 (CET) Injection-Info: dont-email.me; posting-host="d73dca4a29c009ded0dfaf358298d77d"; logging-data="1313927"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/6Ui5DU/ViwmpgFgq0J8SoeIPE6NjgJEE=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:6vuSsUOcBw4hRDya4hvCHTVcpPc= In-Reply-To: Content-Language: en-US On 03.03.2025 01:42, Richard Damon wrote: > On 3/2/25 12:51 PM, WM wrote: > No, it means the set of REQUIRED FISONs is empty, not that we can't use > a set of FISONs to make N. Every set of FISONs which is assumed to be ℕ must have a first element. No FISON can serve as such. That is proven by induction. > >> I did: UF = ℕ ==> Ø = ℕ. > > But you didn't. You showed that there are no specific FISON requried to > be in that set. I proved there is no FISON in that set that could be used with more reason than a cup of coffee. I did it by induction because then I can refer to Zermelo's construction of his potentially infinite sequence of numbers Z₀. Of course it follows also directly by ∀n ∈ Z₀: |ℕ \ {1, 2, 3, ..., n}| = ℵo with Cantor's actually infinite ℕ. Regards, WM