Hi, This is wrong:
sage: A= SteenrodAlgebra(3) sage: x= A.Q(0) sage: y= x.coproduct(); y # that's fine: 1 # Q_0 + Q_0 # 1 sage: x^2 # that's also true: 0 sage: y^2 # gives a wrong answer 2*Q_0 # Q_0 Now y^2 should be zero because the coproduct is an algebra homomorphism. Evidently the issue is with the fact that the Steenrod algebra is a *graded* Hopf algebra, so the multiplication on A # A is NOT the obvious one: signs should be introduced. Perhaps at least a warning may be printed when multiplying elements of A # A, to the effect that the multiplicitation used is not the signed one? best Pierre -- To post to this group, send an email to [email protected] To unsubscribe from this group, send an email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
