#!/usr/local/bin/cadabra2
{s,r,l,k,m,n}::Indices(vector);
{s,r,l,k,m,n}::Integer(0..d-1);
\Gamma_{#}::GammaMatrix(metric=\delta);
\delta_{m n}::KroneckerDelta;
def post_process(ex):
	sort_product(ex)
	eliminate_kronecker(ex)
	canonicalise(ex)
	collect_terms(ex)
ex:=\Gamma_{s r} \Gamma_{r l} \Gamma_{k m} \Gamma_{m s};
for i in range(3):
	join_gamma(_)
	distribute(_)
factor_in(_, $d$);
collect_factors(ex);