Half-cycle: A new formulation for modelling kidney exchange problems

We introduce the half-cycle formulation (HCF), a new integer programming (IP) model for the kidney exchange problem, which has life-saving applications. In HCF, a cycle (i.e., set of kidney swaps) is represented by two compatible halves. After giving several algorithmic enhancements for HCF, we show through extensive computational experiments with an IP solver that our new model outperforms existing formulations when the cycle size limit is set to 4, 5, or 6, depending on the density of the compatibility graph.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/).