This is documentation for Mathematica 8, which was
based on an earlier version of the Wolfram Language.

# UndirectedGraphQ

 UndirectedGraphQ[g] yields True if the graph g is an undirected graph and False otherwise.
• A graph is undirected if every edge in the graph is undirected.
Test whether a graph is undirected:
UndirectedGraphQ gives False for inputs that are not undirected graphs:
Test whether a graph is undirected:
 Out[1]=
 Out[2]=
 Out[3]=
 Out[4]=
 Out[5]=
 Out[6]=

UndirectedGraphQ gives False for inputs that are not undirected graphs:
 Out[1]=
 Out[2]=
 Scope   (3)
Test undirected and directed graphs:
UndirectedGraphQ gives False for anything that is not an undirected graph:
Test large graphs:
The empty graphs are undirected graphs:
An undirected graph can have self-loops:
A graph is either undirected or directed:
A symmetric adjacency matrix is interpreted to be an undirected graph:
Use DirectedEdges->True to interpret it as a directed graph:
The incidence matrix of an undirected graph has no negative entries:
UndirectedGraphQ gives False for non-explicit graphs:
New in 8