## Features & Development

### Sets can't contain Points

by Christopher Heckman -
Number of replies: 1
Even though Sets are subclasses of Lists, WeBWorK complains about a Set that has a Point in it. It does not complain about a List that has a Point in it, though.

Yes, I know that you can override the order of the Points entered with the Context() command, but this doesn't get rid of duplicate entries in the List(Set). And it's something that authors shouldn't have to worry about; it should be fixed.

For instance, woe to the student whose problem says the correct answer is [(1,2), (1,2)], and when they enter [(1,2)], the answer is counted wrong.
The Set() object implements a finite set of Reals, not of arbitrary objects. See the wiki documentation for the Set Object for details.
Sets are intended for use in the Interval context to handle things like the intersection of the intervals (1,3] and [3,5) (without them, you would have to use something like [3,3]).