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is_tree¶
- is_tree(G)[source]¶
Returns \(True\) if \(G\) is a tree.
A tree is a connected graph with no undirected cycles.
For directed graphs, \(G\) is a tree if the underlying graph is a tree. The underlying graph is obtained by treating each directed edge as a single undirected edge in a multigraph.
Parameters : G : graph
The graph to test.
Returns : b : bool
A boolean that is \(True\) if \(G\) is a tree.
See also
is_arborescence
Notes
In another convention, a directed tree is known as a polytree and then tree corresponds to an arborescence.