3 papers
math.CO2026
The Exact End-Degree Threshold for Finite-Width Directed Hexagonal Grids
Dan Zhu, Zhenhua Lyu
Grid theorems provide a fundamental link between the structure of ends and the existence of grid-like subgraphs in infinite graphs and digraphs. For every fixed width , let $k(n…
math.CO2026
A Sharp Ramsey Theorem for Admissible Colorings of Ordered Cliques
Yanan Hu, Zhenhua Lyu, Chenxi Yang
Let \(f(k)\) be the minimum integer \(N\) such that any red--blue edge-coloring of the ordered complete graph on \(N\) vertices contains a set of \(k\) vertices whose induced color…
math.CO2024
Extremal digraphs containing at most paths of length 2 with the same endpoints
Zejun Huang, Zhenhua Lyu
Given a positive integer , let be the digraph consisting of directed paths of length 2 with the same initial and terminal vertices. In this paper, we study the max…