An ant-based algorithm for annular sorting

We present an ant-based algorithm for spatially sorting objects into an annular structure. The model is minimal, as it requires only stochastic ant behaviour coupled with a pheromone-inspired "attraction-repulsion" mechanism. This is the first annular sorting algorithm to consider the problem of objects with non-uniform size, as well as the situation where objects are pre-sorted. The algorithm consistently generates high-quality annular structures, and is particularly powerful in situations where the initial configuration of objects is similar to those observed in nature. We suggest that this model provides a powerful algorithmic framework, as well as a contribution to the study of "attraction-repulsion" models of animal behaviour.