3-bounded property in a triangle-free distance-regular graph

Yeh-jong Pan, Chih-wen Weng

Let $\Gamma$ denote a distance-regular graph with classical parameters $(D,b,\alpha ,\beta )$ and $D\ge 3$. Assume the intersection numbers $a_1=0$ and $a_2\ne 0$. We show $\Gamma$ is 3-bounded in…