Duality and $χ^<$-Boundedness of Ordered Graphs

Fuente: arXiv
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Main Authors: Čertík, Michal, Nešetřil, Jaroslav
Format: Preprint
Published: 2023
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author Čertík, Michal
Nešetřil, Jaroslav
author_facet Čertík, Michal
Nešetřil, Jaroslav
contents We show that there exists only one duality pair for ordered graphs. We will also define a corresponding definition of $χ^<$-boundedness for ordered graphs and show that all ordered graphs are $χ^<$-bounded and prove an analogy of Gyárfás-Sumner conjecture for ordered graphs. We also prove an analogy of Sparse Incomparability Lemma for ordered graphs. We then use this result to show classes of ordered graphs that form a dense order under ordered homomorphisms. We also show that compared to graphs, ordered graphs have more gaps, defined by consecutive monotone matchings and by even more generic pairs of ordered graphs differing by one isolated edge.
format Preprint
id arxiv_https___arxiv_org_abs_2310_00852
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Duality and $χ^<$-Boundedness of Ordered Graphs
Čertík, Michal
Nešetřil, Jaroslav
Combinatorics
We show that there exists only one duality pair for ordered graphs. We will also define a corresponding definition of $χ^<$-boundedness for ordered graphs and show that all ordered graphs are $χ^<$-bounded and prove an analogy of Gyárfás-Sumner conjecture for ordered graphs. We also prove an analogy of Sparse Incomparability Lemma for ordered graphs. We then use this result to show classes of ordered graphs that form a dense order under ordered homomorphisms. We also show that compared to graphs, ordered graphs have more gaps, defined by consecutive monotone matchings and by even more generic pairs of ordered graphs differing by one isolated edge.
title Duality and $χ^<$-Boundedness of Ordered Graphs
topic Combinatorics
url https://arxiv.org/abs/2310.00852