Bell polynomials in combinatorial Hopf algebras

Ammar Aboud (1) , Jean-Paul Bultel (2) , Ali Chouria (2) , Jean-Gabriel Luque (2) , Olivier Mallet (2)

1 ESI - École Nationale Supérieure d'Informatique [Alger]
2 CA - LITIS - Equipe Combinatoire et algorithmes

Partial multivariate Bell polynomials have been defined by E.T. Bell in 1934. These polynomials have numerous applications in Combinatorics, Analysis, Algebra, Probabilities, etc. Many of the formulae on Bell polynomials involve combinatorial objects (set partitions, set partitions in lists, permutations, etc.). So it seems natural to investigate analogous formulae in some combinatorial Hopf algebras with bases indexed by these objects. The algebra of symmetric functions is the most famous example of a combinatorial Hopf algebra. In a first time, we show that most of the results on Bell polynomials can be written in terms of symmetric functions and transformations of alphabets. Then, we show that these results are clearer when stated in other Hopf algebras (this means that the combinatorial objects appear explicitly in the formulae). We investigate also the connexion with the Faà di Bruno Hopf algebra and the Lagrange-Bürmann formula.

Mots clés: Word symmetric functions; Lagrange inversion; Faà di Bruno algebra; Symmetric functions; Hopf algebras; Bell polynomials

Domaines: Combinatoire [math.CO]

Ammar Aboud, Jean-Paul Bultel, Ali Chouria, Jean-Gabriel Luque, Olivier Mallet. Bell polynomials in combinatorial Hopf algebras. 2016. ⟨hal-00945543v3⟩