Is there a more detailed paper describing the algorithm? The description is very vague in the article. When they pick the two points, is there an evaluation on

Is there a more detailed paper describing the algorithm? The description is very vague in the article. When they pick the two points, is there an evaluation on how much "diversity" increases w/r/t each of the three possible operations, and that's how they choose? edit: thanks @q_revert for linking the paper