This is a great question! I don’t actually know the precise condition for box-diagram-ability of a DAG, but I’ve spent a long time thinking about it; it’s partl

This is a great question! I don’t actually know the precise condition for box-diagram-ability of a DAG, but I’ve spent a long time thinking about it; it’s partly why I wrote that program. It’s not a deterministic algorithm, it’s powered by a SAT solver which may return “UNSAT” indicating failure. If anyone has a better answer I would be _very_ interested in reading about it!