English

The unavoidable drawings of complete multipartite graphs

Combinatorics 2025-09-26 v1

Abstract

In a simple drawing of a graph every pair of edges intersect each other in at most one point, which is either a common endvertex or a proper crossing. For each positive integer nn, Negami identified a drawing BnB_n of the complete bipartite graph Kn,nK_{n,n}, and proved that if NN is sufficiently large, then every drawing of KN,NK_{N,N} contains a drawing of Kn,nK_{n,n} weakly isomorphic to BnB_n. Thus BnB_n is (up to weak isomorphism) the only {\em unavoidable} drawing of Kn,nK_{n,n}. We extend this result to complete multipartite graphs, characterizing their unavoidable drawings.

Keywords

Cite

@article{arxiv.2509.20625,
  title  = {The unavoidable drawings of complete multipartite graphs},
  author = {Jozsef Balogh and Irene Parada and Gelasio Salazar},
  journal= {arXiv preprint arXiv:2509.20625},
  year   = {2025}
}
R2 v1 2026-07-01T05:55:06.849Z