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On 28.01.2025 10:19, joes wrote:No, any infinite set of FISON succeeds at having its union be the set N, what can't be done is pare that down to a "minimal" set, as the minimal set will still need to be countably infinite, and all countably infinite sets have the same "size" so none can be the "smallest"Am Tue, 28 Jan 2025 09:58:14 +0100 schrieb WM:But any set of FISONs fails.On 27.01.2025 18:10, joes wrote:Yes it does. Any infinite set of FISONs has a first element.Am Mon, 27 Jan 2025 15:33:01 +0100 schrieb WM:>But no set of FISONs the union of which is ℕ has a first element.Also an infinite set needs a first element.No problem, any infinite set of FISONs has one.
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But that operation can't be done, your logic removes one by one, and thus can't remove ALL.When every not necessary or not useful element has been discarded nothing remains.If anNo, as you have shown, no element is necessary.
infinite set was existing, you could easily find a first not completely
useless element.
Regards, WM
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