Solution
= Solution
Using <set difference> as an <intersection> with a <complement of a set>, and using <double negation>, gives
$$
\begin{aligned}
\overline A\oplus\overline B
&=(\overline A\cap B)\cup(\overline B\cap A)\\
&=(B\setminus A)\cup(A\setminus B)
=A\oplus B.
\end{aligned}
$$
Interchanging the two <sets> simply interchanges the two terms of this <union>, whose <commutativity> gives
$$
\boxed{\overline A\oplus\overline B=A\oplus B,
\qquad A\oplus B=B\oplus A.}
$$