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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb., 2026 Volume 217, Number 1, Pages 114–138 (Mi sm10201)

On nonexistence of negative weight derivations on moduli algebras: Yau's conjecture

B. Chena, S. S.-T. Yaubc

a Department of Mathematics, Sun Yat-sen University, Guangzhou, P.R. China
b Department of Mathematical Sciences, Tsinghua University, Beijing, P.R. China
c Beijing Institute of Mathematical Sciences and Applications, Beijing, P.R. China

Abstract: Let $A=\mathbb{F}[x_1,\dots,x_n]/(f_1,\dots,f_n)$ be a graded complete intersection Artinian algebra where $\mathbb{F}$ is a field of characteristic zero. The grading on $A$ induces a natural grading on $\operatorname{Der}_{\mathbb{F}}(A)$. Halperin proposed a famous conjecture: $\operatorname{Der}_{\mathbb{F}}(A)_{<0}=0$, which implies the collapsing of the Serre spectral sequence for an orientable fibration with fibre an elliptic space with no cohomology in odd degrees. In the context of singularity theory the second author proposed the same conjecture in the special case when $f_i=\partial f/\partial x_i$ for a single polynomial $f$.
H. Chen, the second author and Zuo [5] proved Halperin's conjecture assuming that the degrees of the $f_i$ are bounded below by a constant depending on the number $n$ of variables and the degrees of variables. In this paper, in the special case when $f_i=\partial f/\partial x_i$ for a single polynomial $f$, we refine their result by giving a better bound, which is independent of $n$.

Keywords: Halperin's conjecture, Artinian algebras, derivations of negative weight.

MSC: 14B05, 55P62

Received: 20.09.2024 and 22.04.2025

DOI: 10.4213/sm10201



© Steklov Math. Inst. of RAS, 2026