Hi, I wanted to implement a rule to replace the product of two epsilon tensors with the determinant of a matrix of metric tensors. I found that simplify_indexed works fine but only if at least one of the indices is summed over - calling it on an expression like lorentz_eps(mu,nu,rho,sigma)*lorentz_eps(alpha,beta,gamma,delta) results in no simplification. Implementing this would be no problem if it weren't for the fact that the expression I want to make the replacement in has many instances of lorentz_eps called with different combinations of co- and contra-variant indices - it seems when I call subs, I need to specify the variance of the wildcard in order to make the match so that, for example, ex test = lorentz_eps(mu.toggle_variance(),nu,rho,sigma) test.subs(lorentz_eps(varidx(wildcard(1),4),varidx(wildcard(2),4),varidx(wildcard(3),4),varidx(wildcard(4),4))== #expression#) does not result in any substitution being made. I am not so keen on implementing separate substitutions for all the different combinatoric possibilities of index variances - is there perhaps a simpler way? Thanks for your help, Matthew