I find these problems easy enough to understand, I just have trouble with proofs that make sense.
For example, if I wanted to prove:
Can I write:
or
and
Hence,
I am struggling to understand the following.First, usually denotes conjunction, which joins propositions, not sets. (Speaking of this, it's not good to use both and "and", as well as - and .) Second, I don't see how the right-hand side immediately follows from the definition of the left-hand side.