Show that the set of connectives $\{\wedge, \leftrightarrow, \oplus\}$ is adequate, where $\oplus$ is defined by the truth table:
$\begin{array}{|c | c | c |} \hline p & q & p \oplus q \\ \hline 1 & 1 & 0 \\ \hline 1 & 0 & 1 \\ \hline 0 & 1 & 1 \\ \hline 0 & 0 & 0 \\ \hline \end{array}$
I've been trying all day and for the life of me I can't get my head around this concept of proving a set of connectives to be adequate. I've read every written answer on stackexchange and nothing quite explains it. If I could get some help on this I would truly appreciate it.