What are the edges in the one$-$mode projection of the birthday party a$$iliation network onto the child nodes? $($You can write out the edge list.$)$

$($A$,$R$),($A$,$S$),($A$,$E$),($D$,$E$),($D$,$R$),($D$,$S$),($E$,$R$),($E$,$S$),($K$,$A$),($K$,$R$),($K$,$E$),($R$,$S$)$