(1)Upper bound of S1 = { 3 , 4 , 5 , 6 , 7 , 8 }
A lower bound of S1 =not Exists
Upper bound of S2 = { 6 , 7 , 8 }
Lower bound of S2 = { 1, 2, 3 }
(2)GLB(S1)=not Exists
LUB(S1)=3
GLB(S2)= 3
LUB(S2)=not Exist as both 6 and 7 are upper bounds and they are not related.