I've got a list of items some of which will go into an undetermined number of subsets. An item can be in at most one subset. An item might not end up in a subset.
It's easy if there is always at most 1 subset. It makes it more difficult since there could be more (up to the number of items in the list). Can anyone point me to a good example?
Edit: To put it simpler, the user will be presented with a long list of items. The user will want to group some of them together into distinct groups. Each item in the list may or may not be grouped. If an item does get placed into a group, it can't be placed in a different group. (Or said another way, an item in the list can only be in zero or one groups).