The signs of the generators, see lieAlgebra(..., genSigns => ...) define the sign of an arbitrary expression. The sign of the zero element, L.zz, is defined to be 0. However, the sign of zero should be thought of as arbitrary.
i1 : L = lieAlgebra({a1,a2},genSigns => {1,0}) o1 = L o1 : LieAlgebra |
i2 : signLie (a1 a1) a2 o2 = 0 |
i3 : signLie{a2,a1 a1 a1,a2 a1 a2 + 2 a2 a2 a1} o3 = {0, 0, 1} o3 : List |