Combining Results using Set Operations

Results sets are created by issuing queries. To combine them using logical operations, go to the "Combine results" box, and choose two sets consisting of classes.

Next choose a logical operation:

• "and" does intersection: the result will be those classes that appear in both sets.
• "or" does union: the two sets will be added together, with duplicates removed
• "but not" does minus: starting with the first set, if any of its classes match those in the second set, those classes are removed.