Re: The set of necessary FISONs

Am Sun, 16 Feb 2025 11:31:49 +0100 schrieb WM:

On 15.02.2025 18:38, joes wrote:

Am Sat, 15 Feb 2025 15:55:55 +0100 schrieb WM:

On 15.02.2025 14:40, Richard Damon wrote:

The set you show is empty, is the set of FISONs that are individually
not necessary.

The remaining set should have at least one element.

Indeed, if you remove any number of FISONs, infinitely many remain.

Induction proves an inductive set F of FISONs that can be removed
without changing the result U(F) = ℕ ==> U(F\F) = ℕ.

No. It proves that it doesn’t matter *which single element* is removed.
It proves nothing about removing multiple.

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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.