Cardinal Arithmetic Example Wikipedia

246 Views Asked by At

Hello I am studying cardinal arithmetic, and found out that: $$\mathfrak{c}^{\aleph_0} = (2^{\aleph_0})^{\aleph_0} = 2^{\aleph_0 \aleph_0} = 2^{\aleph_0} = \mathfrak{c} $$

However I found this equivalence in Wikipedia:

$$\mathfrak{c}^{\aleph_0} = \aleph_0^{\aleph_0} = n^{\aleph_0} = \mathfrak{c}^{n} = \aleph_0 \mathfrak{c} = n\mathfrak{c} = \mathfrak{c}$$

where $n$ is any finite cardinal $\geq 2$.

I do not know how they got each line of those equivalences. Could somebody help, please?

Thanks

1

There are 1 best solutions below

0
On

The approach used by tetori in the comments works fine:

$$\mathfrak c \le \mathfrak c^n \le \mathfrak c^{\aleph_0} = (2^{\aleph_0})^{\aleph_0} = 2^{\aleph_0} = \mathfrak c$$

$$\mathfrak c \le n \mathfrak c \le \aleph_0 \mathfrak c \le \mathfrak c^2 = \mathfrak c$$