IJPAM: Volume 49, No. 3 (2008)

A DISTANCE-REGULAR GRAPH WITH INTERSECTION
ARRAY $\{4,2,2,1,1,1;1,1,1,2,2,4\}$ DOES NOT EXIST

M.R. Alfuraidan
Department of Mathematics and Statistics
King Fahd University of Petroleum and Minerals
P.O. Box 1285, Dhahran 31261, KINGDOM OF SAUDI ARABIA
e-mail: monther@kfupm.edu.sa


Abstract.We prove that a distance-regular graph with intersection array $\{4,2,2,1,1,1;1,1,1,2,2,4\}$ does not exist. The proof is purely combinatorial and computer free.

Received: August 14, 2008

AMS Subject Classification: 05E30, 05C12

Key Words and Phrases: distance-regular graph, intersection array

Source: International Journal of Pure and Applied Mathematics
ISSN: 1311-8080
Year: 2008
Volume: 49
Issue: 3