Neighborhoods

Functions for computing neighborhoods of vertices and sets of vertices.

are_neighbors(G, u, v)	Returns true if u is adjacent to v.
closed_neighborhood(G, v)	Return a list with v and of all neighbors of v.
common_neighbors(G, nodes)	Returns a list of all nodes in G that are adjacent to every node in nodes.
neighborhood(G, v)	Return a list of all neighbors of v.