And I am right in saying that (A -B) ∪ (B - A) is equivalent to (A ∪ B) - (A ∩ B) ?
That is correct.
Originally Posted by Nombredor
And And is it accurate to say that (A ∩ Ω) ∪ ~B is the same as Ω - B ?
If ~B means $\displaystyle B^c$, the complement of $\displaystyle B$ then no.
$\displaystyle (A\cap\Omega )\cup B^c=A\cup B^c$ which is not necessarily $\displaystyle B^c~.$
The only thing I've ever seen big-omega used for in set theory is as another name for omega-1 (first uncountable ordinal). Does it also mean "universal set" in the context of intro set theory, then?