On bialgebras and Hopf algebras of oriented graphs
arXiv:1011.3032
Abstract
We define two coproducts for cycle-free oriented graphs, thus building up two commutative con- nected graded Hopf algebras, such that one is a comodule-coalgebra on the other, thus generalizing the result obtained previously for Hopf algebras of rooted trees.
7 pages, error on Proposition 1 corrected, one figure added