i1 : S = QQ[a,b,c,d];
i2 : M = monomialIdeal (b^2, b*c, c^2); o2 : MonomialIdeal of S
i3 : L = lcmLattice (M);
i4 : L.GroundSet 2 2 2 2 2 2 o4 = {b , b*c, c , b c, b c , b*c } o4 : List
The object GroundSet is a symbol.