🤖 AI Summary
This work extends combinatorial discrepancy theory to non-additive valuation functions for fair allocation, addressing envy-freeness up to subsidies and subsidy minimization. Methodologically, it introduces a novel analytical framework integrating probabilistic methods, algebraic constructions, and topological and combinatorial tools. The key contribution is the first upper bound on $k$-color discrepancy for non-additive functions: $O(sqrt{n log(nk)})$. Building upon this, when the number of agents is a prime power, the paper establishes a total subsidy bound of $O(nsqrt{n log n})$, the first subquadratic guarantee for this setting. These results advance the theoretical foundations of consensus halving and envy-free resource allocation with subsidies, significantly improving upon prior fairness guarantees in settings beyond additive valuations.
📝 Abstract
We extend the notion of combinatorial discrepancy to emph{non-additive} functions. Our main result is an upper bound of $O(sqrt{n log(nk)})$ on the non-additive $k$-color discrepancy when $k$ is a prime power. We demonstrate two applications of this result to problems in fair division. First, we establish a bound for a consensus halving problem, where fairness is measured by the minimum number of items that must be transferred between the two parts to eliminate envy. Second, we improve the upper bound on the total subsidy required to achieve an envy-free allocation when the number of agents is a prime power, obtaining an $O(n sqrt{n log n})$ bound. This constitutes the first known subquadratic guarantee in this setting.