Counting unlabeled acyclic digraphs

  • R. W. Robinson
Conference paper
Part of the Lecture Notes in Mathematics book series (LNM, volume 622)


The previously known ways to count acyclic digraphs, both labeled and unlabeled, are reviewed. Then a new method of enumerating unlabeled acyclic digraphs is developed. It involves computing the sum of the cyclic indices of the automorphism groups of the acyclic digraphs, achieving a considerable gain in efficiency through an application of the inclusion-exclusion principle. Numerical results are reported on, and a table of the numbers of unlabeled acyclic digraphs on up to 18 points is included.


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Copyright information

© Springer-Verlag 1977

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  • R. W. Robinson

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