(data structure)
Definition: A graph whose edges are unordered pairs of vertices. That is, each edge connects two vertices.
Formal Definition: A graph G is a pair (V,E), where V is a set of vertices, and E is a set of edges between the vertices E ⊆ {{u,v} | u, v ∈ V}. If the graph does not allow self-loops, adjacency is irreflexive, that is E ⊆ {{u,v} | u, v ∈ V ∧ u ≠ v}.
See also directed graph, hypergraph, multigraph.
Note: An undirected graph may be represented as a directed graph with two directed edges, one "to" and one "from," for each undirected edge.
Author: PEB
If you have suggestions, corrections, or comments, please get in touch with Paul Black.
Entry modified 18 October 2007.
HTML page formatted Mon Feb 2 13:10:40 2015.
Cite this as:
Paul E. Black, "undirected graph", in
Dictionary of Algorithms and Data Structures [online], Vreda Pieterse and Paul E. Black, eds. 18 October 2007. (accessed TODAY)
Available from: http://www.nist.gov/dads/HTML/undirectedGraph.html