If n is a list/set, then choose returns a list/set of the combinations of the list elements.  If n is a non-negative integer, it is interpreted in the same way as a list of the first n integers.

If m is given, then only combinations of size m are generated; otherwise, all combinations are generated, including the empty combination, that is, the power set is generated and converted to a sorted list. Note that duplicates in the list n are taken into account.

The command with(combinat,choose) allows the use of the abbreviated form of this command.