Bounded Degree Conjecture Holds Precisely for c-Crossing-Critical Graphs with c <= 12

Authors Drago Bokal , Zdeněk Dvořák , Petr Hliněný , Jesús Leaños , Bojan Mohar , Tilo Wiedera

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Author Details

Drago Bokal
  • Department of Mathematics and Computer Science, University of Maribor, Maribor, Slovenia
Zdeněk Dvořák
  • Computer Science Institute, Charles University, Prague, Czech Republic
Petr Hliněný
  • Faculty of Informatics, Masaryk University, Brno, Czech Republic
Jesús Leaños
  • Academic Unit of Mathematics, Autonomous University of Zacatecas, Zacatecas, Mexico
Bojan Mohar
  • Department of Mathematics, Simon Fraser University, Burnaby BC, Canada
  • Institute of Mathematics, Physics, and Mechanics, Ljubljana, Slovenia
Tilo Wiedera
  • Theoretical Computer Science, Osnabrück University, Germany


We acknowledge the supporting environment of the workshop Crossing Numbers: Theory and Applications (18w5029) at the Banff International Research Station, where the fundamentals of this contribution were developed.

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Drago Bokal, Zdeněk Dvořák, Petr Hliněný, Jesús Leaños, Bojan Mohar, and Tilo Wiedera. Bounded Degree Conjecture Holds Precisely for c-Crossing-Critical Graphs with c <= 12. In 35th International Symposium on Computational Geometry (SoCG 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 129, pp. 14:1-14:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)


We study c-crossing-critical graphs, which are the minimal graphs that require at least c edge-crossings when drawn in the plane. For every fixed pair of integers with c >= 13 and d >= 1, we give first explicit constructions of c-crossing-critical graphs containing a vertex of degree greater than d. We also show that such unbounded degree constructions do not exist for c <=12, precisely, that there exists a constant D such that every c-crossing-critical graph with c <=12 has maximum degree at most D. Hence, the bounded maximum degree conjecture of c-crossing-critical graphs, which was generally disproved in 2010 by Dvořák and Mohar (without an explicit construction), holds true, surprisingly, exactly for the values c <=12.

Subject Classification

ACM Subject Classification
  • Theory of computation → Computational geometry
  • Mathematics of computing → Graphs and surfaces
  • graph drawing
  • crossing number
  • crossing-critical
  • zip product


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