Title
On the Turán number of ordered forests.
Abstract
An ordered graph H is a simple graph with a linear order on its vertex set. The corresponding Turán problem, first studied by Pach and Tardos, asks for the maximum number ex<(n,H) of edges in an ordered graph on n vertices that does not contain H as an ordered subgraph. It is known that ex<(n,H)>n1+ε for some positive ε=ε(H) unless H is a forest that has a proper 2-coloring with one color class totally preceding the other one. Making progress towards a conjecture of Pach and Tardos, we prove that ex<(n,H)=n1+o(1) holds for all such forests that are “degenerate” in a certain sense. This class includes every forest for which an n1+o(1) upper bound was previously known, as well as new examples. Our proof is based on a density-increment argument.
Year
DOI
Venue
2019
10.1016/j.jcta.2019.01.006
Journal of Combinatorial Theory, Series A
Keywords
DocType
Volume
Turán problem,Ordered forest,Forbidden submatrix
Journal
165
ISSN
Citations 
PageRank 
0097-3165
0
0.34
References 
Authors
0
4
Name
Order
Citations
PageRank
Dániel Korándi123.45
Gábor Tardos21261140.58
István Tomon300.34
Craig Weidert400.34