Doubling bialgebras of rooted trees

TL;DR

This paper introduces a new doubled bialgebra structure on rooted forests, expanding the algebraic framework for rooted trees with interactions and dual products, building on prior constructions.

Contribution

It defines the doubling of two existing bialgebra structures on rooted forests and constructs interacting bialgebras and dual associative products, extending previous work on rooted trees and graphs.

Findings

Constructed two interacting bialgebra structures on doubled spaces.

Established dual associative products related to these bialgebras.

Proved the commutative diagram analogous to previous rooted tree and graph cases.

Abstract

The vector space spanned by rooted forests admits two graded bialgebra structures. The first is defined by A. Connes and D. Kreimer using admissible cuts, and the second is defined by D. Calaque, K. Ebrahimi-Fard and the second author using contraction of trees. In this article we define the doubling of these two spaces. We construct two bialgebra structures on these spaces which are in interaction, as well as two related associative products obtained by dualization. We also show that these two bialgebras verify a commutative diagram similar to the diagram verified D. Calaque, K. Ebrahimi-Fard and the second author in the case of rooted trees Hopf algebra, and by the second author in the case of cycle free oriented graphs.