Regarding null sets, I'm wondering if anyone can explain this $\{\{\emptyset\}\} \subset \{\emptyset, \{\emptyset\}\}$ I don't understand how the left set is a proper set of the right set.
In particular, I'm wondering what the extra brace on the left means and how it is different from say just plain $\{\emptyset\}$. It seems if I disregard the outer brace in the left hand set, my answer matches that of the answer key (namely, true).
I'm posting this again because it was in the wrong stackexchange.
Thanks!
Best Answer
The only element of $\{\{\varnothing\}\}$ is $\{\varnothing\}$ which is in $\{\varnothing, \{\varnothing\}\}$.
Thus it is a subset...