Abstract
We consider a primitive distance-regular graph $$\varGamma $$ with diameter at least 3. We use the intersection numbers of $$\varGamma $$ to find a positive semidefinite matrix G with integer entries. We show that G has determinant zero if and only if $$\varGamma $$ is Q-polynomial.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have