English

A counterexample to DG version of Han's conjecture

Rings and Algebras 2025-12-16 v1 Algebraic Geometry K-Theory and Homology

Abstract

In 2004, Han proposed the following conjecture: let BB be a finite-dimensional kk-algebra. If HHn(B)0\mathrm{HH}_{n}(B)\neq 0 for only finitely many nZn\in \mathbb{Z}, then BB is smooth. This conjecture can be generalized to the DG setting: let BB be a finite-dimensional DG kk-algebra. If HHn(B)0\mathrm{HH}_{n}(B)\neq 0 for only finitely many nZn\in \mathbb{Z}, then BB is smooth. In this note, we show that the DG generalization of Han's conjecture is false.

Cite

@article{arxiv.2512.12460,
  title  = {A counterexample to DG version of Han's conjecture},
  author = {Yeqin Liu and Yu Shen},
  journal= {arXiv preprint arXiv:2512.12460},
  year   = {2025}
}
R2 v1 2026-07-01T08:23:39.609Z