Yep, thanks. I realize that in graph theory trees aren't directed, but in programming, saying "tree" almost always implies a parent-child relationship (i.e, dir

Yep, thanks. I realize that in graph theory trees aren't directed, but in programming, saying "tree" almost always implies a parent-child relationship (i.e, directedness). I was missing that nodes in a DAG can have two "parents", that makes sense.