I´m trying to learn how to find the number of supremum(s) of a set with defined number of elements in it.
Assume A = {1,2,3,4,5,6} and let R be relation defined on power set P(A), so 2 subsets X,Y of A are in relation if X is subset of Y.
Now M = {{1},{2},{2,5}}. How can I find, how many supremum(s) does M have, with exactly 4 elements in it?
How can I create a Hasse diagram from this representation to help solving this (if necessary)?