## young_project_product

Project all tensors in a product with their Young tableau projector.

Project all tensors in a product with their Young tableau
projector. Each factor is projected in turn, after which the product
is distributed and then canonicalised. This is often faster and more
memory-efficient than first projecting every factor and then
distributing.
Young projection can be used to find equalities between tensor
polynomials which are due to multi-term symmetries, such as the Ricci
identity in the example below.{a,b,c,d}::Indices.
R_{a b c d}::RiemannTensor.
ex:=2 R_{a b c d} R_{a c b d} - R_{a b c d} R_{a b c d};

\(\displaystyle{}2R_{a b c d} R_{a c b d}-R_{a b c d} R_{a b c d}\)

young_project_product(_);

\(\displaystyle{}0\)