Neighbourhood
For a undirected graph
the neighbourhood of is ( , ). Sometimes this will be defined to include or exclude - this is called open and closed neighbourhoods.
Directed graph
In a directed this would normally be specified inbound or outbound neighbourhoods.
Inbound / outbound neighbourhood
For a directed graph
and we define:
- the inbound neighbourhood of
to be , and - the outbound neighbourhood of
to be , and - the neighbourhood of
to be .