Definition 2 (Virtual directededge).
In a dynamic virtual digraph DVD(V, E),
virtual edge e E E is an arc from one dynamic node u to another dynamic node v,
where u, vAV.
There is a virtual edge from node u to node v if and only if node u has obtained the public key of v in some kind of authenticated manner.
The virtualdirectededgeisquitedifferentfromthatina
traditional graphinwhichthenodesarestaticandthetopologyof
the graphisnotchangedatall.InDVD,thenodesmaybemoving
and graphtopologymaybechangedatanymoment.Thetradi-
tional edgebetweennodespaircannotbeprospected,butthe
virtual directededgedefinedhereisnotaffectedbythechangein
graph topology.