Expanding is an option for Calc, Contract,
DiracSimplify, DotSimplify,
SUNSimplify etc. As option for Contract it
specifies whether expansion w.r.t. LorentzIndex is done
before contraction. If set to False in
DiracSimplify or SUNSimplify, only a limited
set of simplifications (multiplicative linearity etc.) is performed.
Overview, Calc, Contract, DiracSimplify, DotSimplify, SUNSimplify.