#!/usr/local/bin/cadabra2
{ a, b, c, d }::Indices;
ex:= A_{a b} B_{b c};
substitute(_, $B_{a b} ->  C_{a b c} D_{c}$ );
\dot{#}::Accent;
A_{\dot{a} \dot{b}}::AntiSymmetric;
ex:= A_{\dot{b} \dot{a}};
canonicalise(_);
{ a_{1}, a_{2}, a_{3}, a_{4} }::Indices(vector);
ex:= V_{a_{1}} W_{a_{1}};
substitute(_, $V_{a_{2}} -> M_{a_{2} a_{1}} N_{a_{1}}$ );
R_{a b c d}::TableauSymmetry(shape={2,2}, indices={0,2,1,3}).
ex:=R_{a b c d} R_{d c a b};
canonicalise(_);
{m,n,p,q,r}::Indices(position=free);
\nabla{#}::Derivative;
\partial{#}::PartialDerivative;
A_{m n}::AntiSymmetric;
V_{m}::Depends(\nabla{#});

ex:= \partial_{m p}( A_{q r} V_{n} ) A^{p m};
canonicalise(_);
ex:=\nabla_{m p}( A_{q r} V_{n} ) A^{p m};
canonicalise(_);
unwrap(_);