FCSymmetrize
FCSymmetrize[expr, {a1, a2, ...}]
symmetrizes expr with respect to the variables a1,a2, ...
.
See also
Overview, FCAntiSymmetrize.
Examples
FCSymmetrize[f[a, b], {a, b}]
21(f(a,b)+f(b,a))
FCSymmetrize[f[x, y, z], {x, y, z}]
61(f(x,y,z)+f(x,z,y)+f(y,x,z)+f(y,z,x)+f(z,x,y)+f(z,y,x))