Thread: Least Upper Bound

1. Least Upper Bound

Consider the Hasse diagram shown below. What is the least upper bound for the subset {c, d, e}?

The upper bounds for {c, d, e} are f, g, h. But what is the least upper bound? My friend says the least upper bound does not exist. I say the least upper bound is h because it is related to f and g.

Which one of us is right?

2. You are correct.