Hi there, good point. I didn't explain myself very well. You can do this with intigi, too. You can filter both at the content and the source level. So you could

Hi there, good point. I didn't explain myself very well. You can do this with intigi, too. You can filter both at the content and the source level. So you could set up an interest that presents you with results that a) appear in the HN RSS feed AND b) that don't appear in the r/politics feed In order to do set operations on URLs reliably, we also solve the issue of canonicalization (resolving redirects, removing tracking markers, etc.).