You are right, I also just figured that out. They did not simply mean above in the sense of higher above the table but taking into account the edge structure, should have though about it in terms of monotone functions.
Yeah I've always found these examples are kind of a Sorting Hat for math students. I find the monotone functions definition much more intuitively graspable but a lot of people find the N-cube definition or the subset definition much more amenable.
