Graphs with girth 9 and without longer odd holes are 3‐colourable.

For a number l≥2, let Gl denote the family of graphs which have girth 2l+1 and have no odd hole with length greater than 2l+1. Wu, Xu and Xu conjectured that every graph in ⋃l≥2Gl is 3‐colourable. Chudnovsky et al., Wu et al., and Chen showed that every graph in G2, G3 and ⋃l≥5Gl is 3‐colourable, respectively. In this paper, we prove that every graph in G4 is 3‐colourable. This confirms Wu, Xu and Xu's conjecture. [ABSTRACT FROM AUTHOR]