On Mon, Aug 3, 2009 at 6:15 PM, Kip Murray<[email protected]> wrote: > Do J sets need to be ordered? Fraser believes not, and I will try to persuade > him otherwise following his note below. >
Kip, In the implementation of set-math in J it is necessary to order the representations of sets. I don't see any problem including this step "at creation" of each set, but it's mathematically equivalent to sort (or even cull duplicates) whenever some function takes a set as an argument. The need to sort is a side-effect of a language feature in J: J imposes an ordering on all collections by having a single datatype (array). Sorting each thing that represents a set is just the easiest way to compensate for that inherent structure. In saying that, I don't think I've contradicted or corrected anything you've said. I think I'm making roughly the same point. Tracy ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
