Regular Two-Graphs and Extensions of Partial Geometries

摘要

The paper studies two-graph geometries. These are geometries that carry a regulartwo-graph, but also constitute one-point extensions of partial geometries. First it develops some theory, then it goes through lists of known regular two-graphs and partial geometries in order to find examples. Some are found, including one that extends the partial geometry with parameters s=4, t=17, alpha=2.