Subconstituents of orthogonal graphs of odd characteristic - continued

The subconstituents of the orthogonal graph O(2 nu + delta, q), where nu >= 2 and delta is an element of (1, 2), over a finite field of odd characteristic are shown to be quasi-strongly regular. Furthermore, the first subconstituent is shown to be co-edge regular, and when nu >= 3 its automorphism group is determined. The second subconstituent is shown to be edge regular, and when nu >= 2 its automorphism group is determined. Their parameters and chromatic numbers are also determined. Crown Copyright (C) 2013 Published by Elsevier Inc. All rights reserved.