# networkx.algorithms.tree.recognition.is_forest¶

is_forest(G)[source]

Returns True if G is a forest.

A forest is a graph with no undirected cycles.

For directed graphs, G is a forest if the underlying graph is a forest. 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 – A boolean that is True if G is a forest.

Return type

bool

Notes

In another convention, a directed forest is known as a polyforest and then forest corresponds to a branching.