Representations of Bound Quivers over π½1 and Hall Algebras
Abstract
Representations of quivers over the virtual field π½1 can be naturally extended to bound quivers with monomial and commutativity relations. In this paper, we introduce and study the Hall algebra βπ½1(Q,I) for a bound quiver (Q,I) equipped with such relations. As in the quiver setting, βπ½1(Q,I) is a graded, connected, and cocommutative bialgebra, and the free subgroup generated by all indecomposable representations forms a Lie subalgebra. We study βπ½1(Q,I) in detail for two special classes of bound quivers: Nakayama bound quivers and gentle one-cycle bound quivers. In both cases, we prove that for any triple $L, M, N$ of π½1-representations over (Q,I), the Hall number gN,LM coincides with the evaluation of the corresponding Hall polynomial ΟN,LM(t) at t=1. Consequently, there exists a canonical isomorphism between βπ½1(Q,I) and the degenerate Hall algebra β1(Q,I), justifying Tits's π½1-philosophy in these settings.
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BibTeX
@misc{fu2026representations,
title = {{Representations of Bound Quivers over $\mathbbF_1$ and Hall Algebras}},
author = {Changjian Fu and Xuelian Xiao},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.02904},
eprint = {2611.02904},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.02904},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Representations of Bound Quivers over π½_1 and Hall Algebras
AU - Changjian Fu
AU - Xuelian Xiao
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.02904
UR - https://arxiv.org/abs/2611.02904
AB - Representations of quivers over the virtual field π½_1 can be naturally extended to bound quivers with monomial and commutativity relations. In this paper, we introduce and study the Hall algebra β_π½_1(Q,I) for a bound quiver (Q,I) equipped with such relations. As in the quiver setting, β_π½_1(Q,I) is a graded, connected, and cocommutative bialgebra, and the free subgroup generated by all indecomposable representations forms a Lie subalgebra. We study β_π½_1(Q,I) in detail for two special classes of bound quivers: Nakayama bound quivers and gentle one-cycle bound quivers. In both cases, we prove that for any triple $L, M, N$ of π½_1-representations over (Q,I), the Hall number g_N,L^M coincides with the evaluation of the corresponding Hall polynomial Ο_N,L^M(t) at t=1. Consequently, there exists a canonical isomorphism between β_π½_1(Q,I) and the degenerate Hall algebra β_1(Q,I), justifying Tits's π½_1-philosophy in these settings.
ER -