simple graph
mathematical graph without loops and parallel edges
edgeless graph
graph without edges (on any number of vertices)
Grassmann graph
class of simple graphs defined from vector spaces
directed acyclic graph
directed graph with no directed cycles
order-zero graph
the unique graph having no vertices
unit distance graph
node-link graph of points in the plane, adjacent when their distance is exactly one
acyclic graph
undirected graph having no graph cycles that may be connected or non-connected