1.NounThe branch of mathematics dealing with the properties of graphs (networks of vertices and edges)."The type of graph studied in graph theory is formally described as an ordered pair
G
=
(
V
,
E
)
{\displaystyle G=(V,E)}
comprising a set
V
{\displaystyle V}
of vertices, or nodes, and a set
E
{\displaystyle E}
of pairs (either ordered or unordered) of vertices, each representing an (directed or undirected) edge; if desired, the vertices and/or edges can be labelled."