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arXiv · 2301.06479

Combinatorial Hopf algebras from restriction species with preorder cuts

Gunnar Fløystad
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Abstract

We get new Hopf algebras (HA): 1. A wealth of quotient HA's of the Malvenuto-Reutenauer HA (the Loday-Ronco HA being a special case). They consist of the permutations avoiding an {\it arbitrary} set of permutations without global descents, 2. A HA of pairs of parking filtrations, and 3. Four HA of pairs of preorders. New concepts in this setting are: 1. a category Set$_{\mathbb N}$ whose objects are sets, but morphisms are represented by matrices of natural numbers, and 2. restriction species ${\mathsf S}$ on sets coming with pairs of natural transformations $π_1, π_2 : {\mathsf S} \rightarrow$ Pre to the species of preorders. These induce two coproducts $Δ_1$ and $Δ_2$. Dualizing $Δ_1$ gives product $μ_1$ and coproduct $Δ_2$, giving bimonoid species.

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Gunnar Fløystad. 2026-04-15. Combinatorial Hopf algebras from restriction species with preorder cuts. https://doi.org/10.1016/j.aam.2026.103055

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