Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We prove that a sufficient condition for the core existence in a n-firm vertically differentiated market is that the qualities of firms’ products are equispaced along the quality spectrum. This result contributes to see that a fully collusive agreement among firms in such markets is more easily reachable when product qualities are not distributed too asymmetrically along the quality ladder.