isCentral -- Determines if an element is central

• Usage:

  isCentral x or isCentral(x,ncgb)

• Inputs:
  • x, an instance of the type NCRingElement,
  • ncgb, an instance of the type NCGroebnerBasis, a Groebner basis for the NCRing to which x belongs.
• Outputs:
  • a Boolean value,

i1 : B = threeDimSklyanin(QQ,{1,1,-1},{x,y,z})
--Calling Bergman for NCGB calculation.
Complete!

o1 = B

o1 : NCQuotientRing

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

       3          3
o2 = -y +yxz-xyz+x

o2 : B

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

      2        2
o3 = y +yx+xy+x

o3 : B

i4 : isCentral h

o4 = true

i5 : isCentral g

o5 = true