Using equality in the Krein conditions to prove nonexistence of certain distance-regular graphs
نویسندگان
چکیده
We prove the nonexistence of a distance-regular graph with intersection array {74,54,15;1,9,60} and of distance-regular graphs with intersection arrays { 4r3 + 8r2 + 6r + 1,2r(r + 1)(2r + 1),2r2 + 2r + 1;1,2r(r + 1), (2r + 1)(2r2 + 2r + 1)} with r an integer and r 1. Both cases serve to illustrate a technique which can help in determining structural properties for distance-regular graphs and association schemes with a sufficient number of vanishing Krein parameters. © 2007 Elsevier Inc. All rights reserved.
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ورودعنوان ژورنال:
- J. Comb. Theory, Ser. A
دوره 115 شماره
صفحات -
تاریخ انتشار 2008