Improving Curve Complexity Bounds for RAC Point-Set Embeddings of Trees

Determine whether, for every tree T and point set S, one can compute right-angle crossing (RAC) point-set embeddings with any prescribed number of edge crossings while achieving curve complexity strictly less than 9.

Background

Using their topological linear embeddings, the authors construct RAC point-set embeddings of trees with any prescribed number of crossings and curve complexity at most 9 (reducible to 6 when all points are collinear).

They pose the question of whether this curve complexity bound can be further lowered in the general setting.

References

We conclude with some open problems. (2) Is it possible to compute RAC point-set embeddings of trees with any number of edge crossings and curve complexity smaller than 9?

Tangling and Untangling Trees on Point-sets (2508.18535 - Battista et al., 25 Aug 2025) in Section 6, Final Remarks and Open Problems