  It is well known that anomaly cancellation {\it almost} determines the
hypercharges in the standard model. A related (and somewhat more stronger)
phenomenon takes place in Connes' NCG framework: unimodularity (a technical
condition on elements of the algebra) is {\it strictly} equivalent to anomaly
cancellation (in the absence of right-handed neutrinos); and this in turn
reduces the symmetry group of the theory to the standard $SU(3)\times SU(2)
\times U(1)$.
