Almost-bipartite distance-regular graphs with the Q-polynomial property
Michael S. Lang, Paul M. Terwilliger
Abstract
Let G denote a Q-polynomial distance-regular graph with diameter D at least 4. Assume that the intersection numbers of G satisfy ai=0 for 0 ≤ i ≤ D-1 and aD≠ 0. We show that G is a polygon, a folded cube, or an Odd graph.
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