The vertex count of a graph 
is the number of vertices in 
and is also called the graph order.
Common notations are 
and 
. Equivalently, the vertex count is
the cardinality of the vertex
set.
The vertex count of a graph is implemented in the Wolfram Language as VertexCount[g]. The numbers of vertices for many named graphs are given by the command GraphData[graph, "VertexCount"].
