IsEmpty( M, x ) returns true if M has no members, false otherwise

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

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

$\mathrm{IsEmpty}\left(M\right)$

$\mathrm{false}$

$N≔\mathrm{MultiSet}\left(\right)$

$N≔\varnothing$

$\mathrm{IsEmpty}\left(N\right)$

$\mathrm{true}$

The MultiSet/IsEmpty command was introduced in Maple 2016.

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