isCentral -- Determines if an element is central

i1 : B = threeDimSklyanin(QQ,{1,1,-1},{x,y,z})
Warning:  F4 Algorithm not available over current coefficient ring or inhomogeneous ideal.
Converting to Naive algorithm.

o1 = B

o1 : FreeAlgebraQuotient

i2 : g = z^3 + y*z*x - z*y*x - y^3

        3                    3
o2 = - y  + y*z*x - z*y*x + z

o2 : B

i3 : h = x^2 + y^2 + z^2

      2                2
o3 = y  + y*z + z*y + z

o3 : B

i4 : isCentral h

o4 = true

i5 : isCentral g

o5 = true