The poset P is an upper semilattice if every pair of vertices has a unique least upper bound (join).
i1 : n = 4; |
i2 : isUpperSemilattice chain n o2 = true |
i3 : B = booleanLattice n; |
i4 : isUpperSemilattice B o4 = true |
i5 : isUpperSemilattice flagPoset(B, {1,2,3}) o5 = false |
i6 : B' = flagPoset(B, {1,2,3,4}); |
i7 : isLattice B' o7 = false |
i8 : isUpperSemilattice B' o8 = true |