English

Recognition of Unit Segment and Polyline Graphs is $\exists\mathbb{R}$-Complete

Computational Geometry 2025-12-09 v3

Abstract

Given a set of objects OO in the plane, the corresponding intersection graph is defined as follows. Each object defines a vertex and an edge joins two vertices whenever the corresponding objects intersect. We study here the case of unit segments and polylines with exactly kk bends. In the recognition problem, we are given a graph and want to decide whether the graph can be represented as an intersection graph of certain geometric objects. In previous work it was shown that various recognition problems are R\exists\mathbb{R}-complete, leaving unit segments and polylines among the few remaining natural cases where the recognition complexity remained open. We show that recognition for both families of objects is R\exists\mathbb{R}-complete.

Keywords

Cite

@article{arxiv.2401.02172,
  title  = {Recognition of Unit Segment and Polyline Graphs is $\exists\mathbb{R}$-Complete},
  author = {Michael Hoffmann and Tillmann Miltzow and Simon Weber and Lasse Wulf},
  journal= {arXiv preprint arXiv:2401.02172},
  year   = {2025}
}

Comments

23 pages, 15 figures. v3 fixes a mistake in the proof for polylines

R2 v1 2026-06-28T14:08:32.192Z