New Feasibility Conditions for Directed Strongly Regular Graphs

Sylvia A. Hobart, Jason Williford

Abstract


We prove two results for directed strongly regular graphs that have an eigenvalue of multiplicity less than $k$, the common out-degree of each vertex. The first bounds the size of an independent set, and the second determines an eigenvalue of the subgraph on the out-neighborhood of a vertex. Both lead to new nonexistence results for parameter sets.

Keywords


Directed strongly regular graph

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