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category_of_non-crossing_partitions_with_small_blocks

Category of non-crossing partitions with small blocks

The category of non-crossing partitions with small blocks is a a Banica-Speicher category of partitions inducing the corepresentation category of the free bistochastic quantum groups.

Definition

By the category of non-crossing partitions with small blocks one denotes the subcategory of the category of all partitions $\Pscr$ whose morphism set is the set of all non-crossing partitions with small blocks. It was introduced by Banica and Speicher in [BanSp09].

  • A partition $p\in \Pscr$ is said to have small blocks if every block of $p$ has size $1$ or $2$.
  • It is said to be non-crossing if there exist no blocks $B$ and $B'$ of $p$ with $B\neq B'$ and no legs $i,j\in B$ and $i',j'\in B'$ such that $i\prec i'\prec j$ and $i'\prec j\prec j'$ with respect to the cyclic order of $p$. See also category of all non-crossing partitions.
  • The name set of all non-crossing partitions with small blocks is to be taken literally.

Canonical generator

The category of all non-crossing partitions with small blocks is the subcategory of $\Pscr$ generated by the partition $\singleton$.

Associated easy quantum group

Via Tannaka-Krein duality for compact quantum groups, the category of all non-crossing partitions with small blocks corresponds to the family $(B^{+}_N)_{N\in \N}$ of free bistochastic quantum groups.

References


[BanSp09] Banica, Teodor and Speicher, Roland, 2009. Liberation of orthogonal Lie groups. Advances in Mathematics, 222, pp.1461–150.
category_of_non-crossing_partitions_with_small_blocks.txt · Last modified: 2021/11/23 11:56 (external edit)