Graphs & digraphs (2nd ed.)
The asymptotic number of acyclic digraphs
Combinatorica
The asymptotic number of acyclic diagraphs, II
Journal of Combinatorial Theory Series A
Counting acyclic digraphs by sources and sinks
Discrete Mathematics
Asymptotic Behaviour of the Number of Labelled Essential Acyclic Digraphs and Labelled Chain Graphs
Graphs and Combinatorics
Exact enumeration of acyclic deterministic automata
Discrete Applied Mathematics
Well-quasi-ordering hereditarily finite sets
LATA'11 Proceedings of the 5th international conference on Language and automata theory and applications
Ranking, unranking and random generation of extensional acyclic digraphs
Information Processing Letters
Hi-index | 0.89 |
Transitive sets with n elements were counted by Peddicord in 1962, by the use of Ackermann@?s numeric encoding of a (hereditarily finite) set. In this paper we give a combinatorial interpretation of this number by counting extensional acyclic digraphs. In a similar constructive manner, we also obtain the number of weakly extensional acyclic digraphs with a given number of labeled sinks and a given number of sources, or with a given number of vertices of maximum rank.