On 1/10/07, Samuel Wantman wantman@earthlink.net wrote:
I'm not certain that category unions are nearly as critical. Since all these "index" categories (Americans, Actors, Poets, Writers, etc...) would be fully populated, they would already contain the union of all their sub-categories. The only thing missing would be unions of only some of the subcategories, for instance, the union of Comedy films and Drama films, or Poets and Novelists. For most topics these do not seem very significant.
Not as important as intersections, no. But while I've been bitten for spouting off about stuff I'm ignorant of before, surely calculating a union would be cheaper than calculating an intersection anyway?