# Math Help - Set Theory Help - Simple Question

1. ## Set Theory Help - Simple Question

I have got the following question

(AUC)'\(CnD)

What does the \ mean?

Tried googling and looking in a book but cant find it

2. $A$\ $B$ (or $A-B$) is the relative complement of $A$ in $B$.

$A-B=\{x\in A; x \notin B \}$

3. Set-theoretic difference. The expression $(A\cup C)'\setminus (C\cap D)$ means the set of all elements of $(A\cup C)'$ that are not in $C\cap D$.