A strengthening of Halin's grid theorem
Jan Kurkofka, Ruben Melcher, Max F. Pitz · Mathematika · 2022
We show that for every infinite collection R $\mathcal {R}$ of disjoint equivalent rays in a graph G there is a subdivision of the hexagonal half-grid in G such that all its vertical rays belong to R $\mathcal {R}$ . This result strengthens Halin's grid theorem by giving control over which specific set of rays is used, while its proof is significantly shorter.