On off-diagonal ordered Ramsey numbers of nested matchings
Abstract
For two graphs and with linearly ordered vertex sets, the ordered Ramsey number is the minimum such that every red-blue coloring of the edges of the ordered complete graph on vertices contains a red copy of or a blue copy of . For a positive integer , a nested matching is the ordered graph on vertices with edges for every . We improve bounds on the ordered Ramsey numbers obtained by Rohatgi, we disprove his conjecture by showing for every , and we determine the numbers exactly for . As a corollary, this gives stronger lower bounds on the maximum chromatic number of -queue graphs for every . We also prove for arbitrary and . We expand the classical notion of Ramsey goodness to the ordered case and we attempt to characterize all connected ordered graphs that are -good for every . In particular, we discover a new class of ordered trees that are -good for every , extending all the previously known examples.
Keywords
Cite
@article{arxiv.2201.07637,
title = {On off-diagonal ordered Ramsey numbers of nested matchings},
author = {Martin Balko and Marian Poljak},
journal= {arXiv preprint arXiv:2201.07637},
year = {2022}
}
Comments
17 pages, 7 figures, minor revisions