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

$(\text{'}$A$\text{'},\text{'}$R$\text{'}),(\text{'}$A$\text{'},\text{'}$S$\text{'}),(\text{'}$A$\text{'},\text{'}$E$\text{'}),(\text{'}$D$\text{'},\text{'}$E$\text{'}),(\text{'}$D$\text{'},\text{'}$R$\text{'}),(\text{'}$D$\text{'},\text{'}$S$\text{'}),(\text{'}$E$\text{'},\text{'}$R$\text{'}),(\text{'}$E$\text{'},\text{'}$S$\text{'}),(\text{'}$K$\text{'},\text{'}$A$\text{'}),(\text{'}$K$\text{'},\text{'}$R$\text{'}),(\text{'}$K$\text{'},\text{'}$E $\text{'}),(\text{'}$R$\text{'},\text{'}$S$\text{'})$