English

Lower bounds on the number of envy-free divisions

Combinatorics 2025-05-08 v2 Geometric Topology

Abstract

We analyze lower bounds for the number of envy-free divisions, in the classical Woodall-Stormquist setting and in a non-classical case, when envy-freeness is combined with the equipartition of a measure. 1. In the first scenario, there are rr hungry players, and the cake (that is, the segment [0,1][0,1]) is cut into rr pieces. Then there exist at least two different envy-free divisions. This bound is sharp: for each rr, we present an example of preferences such that there are exactly two envy-free divisions. 2. In the second (hybrid) scenario, there are pp not necessarily hungry players (pp is a prime) and a continuous measure μ\mu on [0,1][0,1]. The cake is cut into 2p12p-1 pieces, the pieces are allocated to pp boxes (with some restrictions) and the players choose the boxes. Then there exists at least (2p1p1)22p\binom{2p-1}{p-1} \cdot 2^{2-p} envy-free divisions such that the measure μ\mu is equidistributed among the players.

Keywords

Cite

@article{arxiv.2504.18979,
  title  = {Lower bounds on the number of envy-free divisions},
  author = {Duško Jojić and Gaiane Panina and Rade Živaljević},
  journal= {arXiv preprint arXiv:2504.18979},
  year   = {2025}
}