Lujia Wang

collaborators

5 papers

math.CO2026

Winding number and circular coloring

Reza Naserasr, Cyril Pujol, Lujia Wang

In 1996, Youngs proved a surprising theorem that quadrangulations of the projective plane could never have chromatic number exactly 3. This sparked a lot of interest, and the resul…

math.CO2025

An Erdos-Gallai conjecture for signed graphs

Lujia Wang

For every natural number $p$ , we show that the maximum negative girth among the class of signed graphs on $n$ vertices with balanced chromatic number at least $p$ is between $(1/e)…

math.CO2025

Colouring signed analogues of Kneser, Schrijver, and Borsuk graphs

Luis Kuffner, Reza Naserasr, Lujia Wang +3

The Kneser signed graph $\KS(n,k)$, $k \leq n$ , is the graph whose vertices are signed $k$ -subsets of $[n]$ (i.e. $k$ -subsets $S$ of ${\pm 1, \pm 2, \dots, \pm n}$ such that $S\…

math.CO2025

Odd Hadwiger's conjecture for the complements of Kneser graphs

Meirun Chen, Reza Naserasr, Lujia Wang +1

A generalization of the four-color theorem, Hadwiger's conjecture is considered as one of the most important and challenging problems in graph theory, and odd Hadwiger's conjecture…

math.CO2025

Fractional balanced chromatic number of signed subcubic graphs

Xiaolan Hu, Luis Kuffner, Jiaao Li +4

A signed graph is a pair $(G, I ¨ )$ , where $G$ is a graph and $I ¨ : E (G) \to {-, +}$ , called signature, is an assignment of signs to the edges. Given a signed graph $(G, I ¨ )$ …