split_gamma
Split a Dirac gamma matrix off a generalised product of gamma matrices.
Given a generalised product of Dirac gamma matrices, rewrite it as a product with an
explicit single gamma matrix. This is the inverse of the join_gamma
algorithm.
An example:\Gamma{#}::GammaMatrix(metric=\eta);
ex:=\Gamma^{m n p};
Attached property GammaMatrix to Γ(#).
Γmnp
split_gamma(_, on_back=False);
ΓmΓnp−Γpηmn+Γnηmp