Double-bosonization and Majid's conjecture (V): grafting of quantum groups
Hongmei Hu, Naihong Hu
TL;DR
The paper develops a multi-tensor extension of Majid's generalized double-bosonization to realize larger Drinfeld–Jimbo quantum groups by grafting two (or more) smaller quantum groups along a connecting node. It constructs a braided-categorical framework using weakly quasitriangular dual pairs and dually-paired braided groups, enabling explicit cross-relations and central extensions on a grafted tensor space. Concrete realizations are provided: a simply-laced Type A graft yielding $U_q(\mathfrak{sl}_{n+m})$ and a non-simply-laced Type F4 graft from $U_q(\mathfrak{sl}_3)\oplus U_q(\mathfrak{sl}_2)$, including $q$-Serre relations and basis analyses. The approach offers a uniform, algebraic method to construct new quantum groups from existing building blocks, with potential extension to affine and indefinite types, connecting to Majid's quantum-tree program.
Abstract
The goal of this paper is to propose and carry out a program which allows us to yield a larger target quantum group of Drinfeld-Jimbo type via grafting two given smaller ones. To this effect, we first set up some basics of a multi-tensor product theory of the generalized double-bosonization construction (see [HH2] for the latter). Such a grafting method, depending on the choice of grafting node in the Dynkin diagram, including rank-induction and type-crossing constructions as special cases, provides a one-stop resolving strategy of the generation question of Majid's quantum tree, which grows up from the root part $U_q(\mathfrak{sl}_2)$ and decorates with the quantum groups of various Dynkin diagrams (of finite types) as the branches.
