Hi

I have done the proof, just need to check it. I wanted to prove that

$\displaystyle A\cap B=A\setminus(A\setminus B)$

Proof:

$\displaystyle \mbox{let}\ x\in A\cap B\ \mbox{be arbitrary}$

$\displaystyle \Rightarrow x \in A\ \mbox{and}\ x \in B $

$\displaystyle \Rightarrow x \in A\ \mbox{and}\ x \notin B^{c} $

$\displaystyle \Rightarrow x \in A\ \mbox{and}\ x \notin A\setminus B$

$\displaystyle \Rightarrow x \in A\setminus (A\setminus B) $

I know that I have to do reverse proof too. But is it ok so far ?

Thanks