Share the Multicast Payment Fairly

In this paper, we study how to share the payments to relay links among the receivers for multicast. Based on a strategyproof mechanism whose multicast tree is at most 2 times the optimal, we propose a payment sharing scheme that is $\frac{1}{n^2}$ -budget-balanced, cross-monotonic, and in the core. We also prove that there is no payment sharing scheme that can achieve β-budget-balance and cross-monotonicity for $\beta= \Omega\frac{1}{n}$ . When both the relay agents and the receivers are selfish, we show a negative result: combining a strategyproof mechanism for the relay agents and a strategyproof sharing scheme for the receivers does not necessarily imply a strategyproof mechanism overall.