For any element m∈A in A and any element x∈S in S = {H, I, F, G}, if the partial order relation m≤x is satisfied, then M is called the lower bound of S.

Because b and g do not satisfy the partial ordering relationship, the same c and g, d and f, e and f do not satisfy the partial ordering relationship.

That is, B ≤ G, C ≤ G, D ≤ F and E ≤ F do not exist, so B, C, D and E are not the lower bounds of S = {H, I, F, G}.