Almost All Regular Graphs are Normal

Abstract

In 1999, De Simone and Körner conjectured that every graph without induced $C_5,C_7,{\overline{C}}_7$ contains a clique cover $\mathcal{C}$ and a stable set cover $\mathcal{I}$ such that every clique in $\mathcal{C}$ and every stable set in $\mathcal{I}$ have a vertex in common. This conjecture has roots in information theory and became known as the Normal Graph Conjecture. Here we prove that all graphs of bounded maximum degree and sufficiently large odd girth (linear in the maximum degree) are normal. This implies that for every fixed $d$, random $d$-regular graphs are a.a.s. normal.

arXiv comment7 pages, 2 figures, submitted to the Journal of Discrete Applied Mathematics