A solid point: books may excel at one dimension while not even attempting another. I suppose one might have to ascertain what genre, exactly, a book falls in, a

A solid point: books may excel at one dimension while not even attempting another. I suppose one might have to ascertain what genre, exactly, a book falls in, and how it fares in its own genre. But then you're not comparing pairwise, and we lose the benefits of our visual cortex or whatever neural system is so good at pairwise comparisons. Constraining pairings within their genres might suffice, if possible. There are several standard ontology for books, and it's not a trivial problem.