Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
For the problem of adjudicating conflicting claims, we develop a new proof of an important result due to Young (1995), a characterization of the proportional rule, rather, we prove a dual characterization of this rule. Our axioms are composition down, which states the equivalence of two ways of dealing with possible decreases in the amount to divide, and self-duality, according to which, for each problem, a rule divides what is available symmetrically to the way it divides what is missing, that is, the difference between the sum of the claims and the endowment, in the dual problem.