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
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Returns: | b : bool
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See also
is_arborescence
Notes
In another convention, a directed tree is known as a polytree and then tree corresponds to an arborescence.