Partially compactified quantum cluster structures on simple algebraic groups and the full Berenstein--Zelevinsky conjecture
Fan Qin, Milen Yakimov
TL;DR
This work provides a general method to lift quantum cluster structures from localizations to partially compactified quantum cluster algebras, enabling constructions on quantized coordinate rings $R_q[G]$ of complex simple groups. By analyzing quantum double Bruhat cells through $S_w^+$ and $S_u^-$ and using Berenstein--Zelevinsky seeds, the authors prove the full Berenstein--Zelevinsky conjecture: all seeds associated to signed words for $(u,w)$ are mutation-connected and yield the same quantum cluster structure. They furthermore develop a principled approach (Theorem C) to recover a noncommutative algebra from a localization, securing a bridge between localized and globally defined cluster structures. The combination of codimension-2 arguments, canonical and triangular bases, and mutation connectivity yields a robust framework for constructing partially compactified quantum cluster algebras on quantized coordinate rings, with direct implications for canonical basis theory and the geometry of double Bruhat cells.
Abstract
The construction of partially compactified cluster algebras on coordinate rings is handled by using codimension 2 arguments on cluster covers. An analog of this in the quantum situation is highly desirable but has not been found yet. In this paper, we present a general method for the construction of partially compactified quantum cluster algebra structures on quantized coordinate rings from that of quantum cluster algebra structures on localizations. As an application, we construct a partially compactified quantum cluster algebra structure on the quantized coordinate ring of every connected, simply connected complex simple algebraic group. Along the way, we settle in full the Berenstein--Zelevinsky conjecture that all quantum double Bruhat cells have quantum cluster algebra structures associated to seeds indexed by arbitrary signed words, and prove that all such seeds are linked to each by mutations.
