Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This paper complements Jia (2019) by proving that the even split rule is the only Pareto efficient allocation that breaks down any concave symmetric supermodular function into two supermodular functions. It further provides an alternative proof for Theorem 1 of Jia (2019), which confirms that the even split rule is necessary to ensure any symmetric supermodular function, regardless its convexity or concavity, could be divided into two supermodular functions.