Dear all, I found out that canonicalizing clifford objects was not functioning properly. This was because a dirac_slash was automatically getting zero as its metric. When canonicalizing clifford objects the anti-commutator of two objects that were ordered in the wrong way is necesary. However, if the metric is automatically set to zero, this anti-commutator is zero too. I fixed this in CVS. I do have two questions about the implementation (1) Why are the indices in dirac_gamma (and with my patch in dirac_slash) static? Does the dimension of them not matter? It now seems that the dimension as used in the metric is always equal to the dimension of the very first dirac_gamma/dirac_slash that is constructed. (2) Why does the metric have indices? In view of the implementation of get_metric the primary purpose of these indices seems to be to be replaced by other indices. If that is the case why are they present in the first place? Best, Chris