symmdiff( M, N ) returns the symmetric difference of M and N, which is (M union N) minus (M intersect N).

At least one argument must be a MultiSet for this routine to be invoked.  Any other argument which is expected to be a MultiSet can be a MultiSet, a set or a list; in the latter two cases the argument is converted to a MultiSet before proceeding to evaluate this command.  IsGeneralized(M) must return the same value for all MultiSet arguments M, and all non-MultiSet arguments will be promoted to MultiSets with this same property.

$M≔\mathrm{MultiSet}\left(a=2\,b=5\,c=4\right)$

$M≔\left\{\left[a\,2\right]\,\left[b\,5\right]\,\left[c\,4\right]\right\}$

$N≔\mathrm{MultiSet}\left(a=4\,c=7\right)$

$N≔\left\{\left[a\,4\right]\,\left[c\,7\right]\right\}$

$\mathrm{symmdiff}\left(M\,N\right)$

$\left\{\left[a\,2\right]\,\left[b\,5\right]\,\left[c\,3\right]\right\}$

The MultiSet/symmdiff command was introduced in Maple 2016.

For more information on Maple 2016 changes, see Updates in Maple 2016.