Koolen et al. showed that if a connected graph with smallest eigenvalue at least −3 has large minimal valency, then it is 2-integrable. In this paper, we will prove that a lower bound for the minimal valency is 166.
@article{arxiv.1806.11325,
title = {On the integrability of strongly regular graphs},
author = {Jack H. Koolen and Masood Ur Rehman and Qianqian Yang},
journal= {arXiv preprint arXiv:1806.11325},
year = {2018}
}