In [1] N.L. Biggs mentions two parameter sets for distance regular graphs that are antipodal covers of a complete graph, for which existence of a corresponding graph was unknown. Here we settle both cases by proving that one does not exist, while there are exactly two nonisomorphic solutions to the
Second neighbourhoods of strongly regular graphs
β Scribed by A.D. Gardiner; C.D. Godsil; A.D. Hensel; Gordon F. Royle
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 723 KB
- Volume
- 103
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
β¦ Synopsis
Some antipodal
distance-regular graphs of diameter three arise as the graph induced by the vertices at distance two from a given vertex in a strongly regular graph. We show that if every vertex in a strongly regular graph G has this property, then G is the noncollinearity graph of a special type of semipartial geometry.
As these semipartial geometries have all been classified, we obtain a list of the antipodal distance-regular graphs of diameter three that can arise in this way.
π SIMILAR VOLUMES
## Abstract We apply symmetric balanced generalized weighing matrices with zero diagonal to construct four parametrically new infinite families of strongly regular graphs. Β© 2003 Wiley Periodicals, Inc. J Combin Designs 11: 208β217, 2003; Published online in Wiley InterScience (www.interscience.wil
In this paper we solve 3 of the 6 problems of A. Kotzig on regular and strongly-regular self-complementary graphs, mentioned in "Graph Theory and Related Topics" edited by J.A.
## Abstract It is shown that certain conditions assumed on a regular selfβcomplementary graph are not sufficient for the graph to be strongly regular, answering in the negative a question posed by Kotzig in [1].