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arXiv · 1711.05874

A new characterization of the dual polar graphs

Zhi Qiao·Jack Koolen
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Abstract

In this paper we give a new characterization of the dual polar graphs, extending the work of Brouwer and Wilbrink on regular near polygons. Also as a consequence of our characterization we confirm a conjecture of the authors on non-bipartite distance-regular graphs with smallest eigenvalue at most $-k/2$, where $k$ is the valency of the distance-regular graph, in case of $c_2 \geq3$ and $a_1 =1$.

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Zhi Qiao, Jack Koolen. 2017-11-17. A new characterization of the dual polar graphs. https://arxiv.org/abs/1711.05874

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