So the homework problem I was doing is as follows:

Answer these questions for the partial order represented by this Hasse diagram.

a)Find the maximal elements.

b)Find the minimal elements.

c)Is there a greatest element?

d)Is there a least element?

e)Find all upper bounds of {a, b, c}.

f )Find the least upper bound of {a, b, c}, if it exists.

g)Find all lower bounds of {f, g, h}.

h)Find the greatest lower bound of {f, g, h}, if it exists.

I know the answers to the first four questions but I don't know what to do for the bounds stuff. I tried reading my textbook but it doesn't make much sense. Can someone please explain this to me? You don't need to necessarilly provide me with the specific answers but if you do please be clear