On ordered Ramsey numbers of matchings versus triangles

Martin Balko, Marian Poljak

Research output: Contribution to journalArticlepeer-review

Abstract

For graphs G< and H< with linearly ordered vertex sets, the ordered Ramsey number r< (G<, H<) is the smallest positive integer N such that any red-blue coloring of the edges of the complete ordered graph KN< on N vertices contains either a blue copy of G< or a red copy of H<. Motivated by a problem of Conlon, Fox, Lee, and Sudakov (2017), we study the numbers r< (M<, K3<) whereM < is an ordered matching on n vertices. We prove that almost all n-vertex ordered matchings M< with interval chromatic number 2 satisfy r< (M<, K3<)∈Ω((n/logn)5/4) and r< (M<, K3<)∈ O(n7/4), improving a recent result by Rohatgi (2019). We also show that there are nvertex ordered matchings M< with interval chromatic number at least 3 satisfying r< (M<, K3<)∈Ω((n/logn)4/3), which asymptotically matches the best known lower bound on these off-diagonal ordered Ramsey numbers for general n-vertex ordered matchings.

Original languageEnglish
Article numberP2.23
JournalElectronic Journal of Combinatorics
Volume31
Issue number2
DOIs
StatePublished - 1 Jan 2024
Externally publishedYes

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Geometry and Topology
  • Discrete Mathematics and Combinatorics
  • Computational Theory and Mathematics
  • Applied Mathematics

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