M minus N returns the set difference (counting multiplicity) between M and 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.

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

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

$N≔\mathrm{MultiSet}\left(a\,b=3\right)$

$N≔\left\{\left[a\,1\right]\,\left[b\,3\right]\right\}$

$M\mathbf{minus}N$

$\left\{\left[a\,1\right]\,\left[b\,2\right]\right\}$

$M\mathbf{minus}\left[b\,a\,a\right]$

$\left\{\left[b\,4\right]\right\}$

The MultiSet/minus operator was introduced in Maple 2016.

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