## CommutingAsSum

Makes an object behave as a sum when commuting.

This makes an object behave, for purposes of commutation rules, as a
sum.A(#)::CommutingAsSum;
{Q,X,Y,Z}::AntiCommuting;
ex:= A(Y)(Z)*A(X);

\(\displaystyle{}\text{Attached property CommutingAsSum to }A(\#).\)

\(\displaystyle{}\text{Attached property AntiCommuting to }(Q, X, Y, Z).\)

\(\displaystyle{}A(Y Z) A(X)\)

sort_product(_);

\(\displaystyle{}-A(X) A(Y Z)\)

The minus sign arises because it would also have been present when
sorting the expression

`(Y+Z)*X`

.