All subsets of $\{1,\{\}\}$ I'm trying to figure out what all subsets of the set $A \colon= \{1,\{\}\}$ are.
I am not sure if the answer is:


*

*$P(A) = \{ \{ \}, \{1\}, \{1;\{\}\}, \{\{\}\} \}$ or

*$P(A) = \{ \{\}, \{1\}, \{1; \{\}\} \}$

Recall that the power set is the set of all subsets of A, including the empty set and A itself therefore in this case
$$P(A) = \Big\{ \{\}, \{1\}, \{\{\}\}, \{1,\{\}\} \Big\}$$
which indeed, since $|A|=n=2$, has $2^n=4$ elements.
