Re: The set of necessary FISONs

On 22.02.2025 11:39, joes wrote:

Am Thu, 20 Feb 2025 19:03:39 +0100 schrieb WM:

On 20.02.2025 12:46, joes wrote:

Am Thu, 20 Feb 2025 11:26:13 +0100 schrieb WM:

>

Subtraction of all elements leaves the empty set.
UF = ℕ ==> Ø = ℕ.

Substitute: UF = X != N. Does it follow that X = {}?

No.

Ok. Why does it follow for N only?

 We know that |ℕ \ {1, 2, 3, ..., n}| = ℵo but not what is
|X \ {1, 2, 3, ..., n}|.
 Regards, WM