ELZBIETA KOWALSKA
A note on link diagraphs
Pages: 51-56
Received: 22 October 1991
Mathematics Subject Classification: 05C20
Abstract
In this note we deal with the outlink (inlink) digraphs.
The outlink (inlink) of a vertex of a digraph is the subdigraph
induced by its outneighbourhood (inneighbourhood). In a digraph
with constant outlink (inlink) all outlink (inlinks) are isomorphic. Then
an outlink (inlink) diagraph is the constant outlink (inlink) of some diagraph.
We prove that a starlike graph has at least two orientations, which are outlink (inlink) digraphs.
As a corollary from the above result, we obtain the affirmative answer to Harary's question, if instars
and outstars are oulink (inlink) digraphs.