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Pseudotree


Pseudotree

A pseudotree is a connected pseudoforest, i.e., an undirected connected graph that contains at most one graph cycle. Connected acyclic graphs (i.e., trees), are therefore pseudotrees.

Some care is needed when encountering pseudotrees as some authors use the term to mean "a pseudotree that is not a tree." Such graphs are perhaps better known as connected unicyclic graphs for clarity.

The numbers of pseudotrees on 1, 2, 3, ... vertices are 1, 1, 2, 4, 8, 19, 44, 112, ... (OEIS A005703), the first few of which are illustrated above.


See also

Acyclic Graph, Forest, Graph Cycle, Pseudoforest, Tree, Unicyclic Graph

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References

Sloane, N. J. A. Sequence A005703/M1151 in "The On-Line Encyclopedia of Integer Sequences."

Cite this as:

Weisstein, Eric W. "Pseudotree." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Pseudotree.html

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