[fifilura]

1. GP mentioned hairy self joins 2. You replied with an example 3. I pointed out that there are other examples.

That said, I have a feeling your duplicates can be fixed by adding the requirement that c.cid < c2.cid

Not sure a window function would help in this particular situation, but they are there to help in more mundane examples.

[weaksauce]

I see how it can be read that way yeah. they mentioned the study used a self join problem that they couldn't likely figure out so I looked at the paper and quickly did it off the top of my head. the less than predicate does indeed do the trick.