Re: The set of necessary FISONs

On 16.02.2025 18:23, joes wrote:

Am Sun, 16 Feb 2025 16:52:00 +0100 schrieb WM:

n.

What are you talking about? There are always inf. many if you remove
a natural number of FISONs, and their union is N.

Induction proves that there is no FISON that, when removed, changes the premise. Therefore all FISONs can be removed without changing the premise. The conclusion is U(F\F) = ℕ.

You DO change the result to the empty set if you remove everything; the
union of all FISONs is not the empty set.

But the union of all FISONs which have the union ℕ is the empty set.

You can only remove a finite
number of them, doesn’t matter which.

Wrong. Learn the meaning of induction.
Regards, WM