On the rigidity of small domains

分次整环及其Veronese子环的刚性

Rigidity of Graded Integral Domains and of their Veronese Subrings

研究分次整环的刚性是否遗传给其Veronese子环，以及子环的导子能否扩展到原环，刻画使Veronese子环非刚性的子群性质。

诺特环上的profinite刚性

Profinite Rigidity over Noetherian Domains

本文研究诺特环上模的profinite刚性，建立基础命题，描述三个不变量，证明在特定条件下自由模和有限生成模的刚性，并应用于可解Baumslag-Solitar群，给出非阿贝尔单关系群和非LERF群中绝对profinite刚性的首批例子。

On the rigidity of certain Pham-Brieskorn rings

Fix a field $k$ of characteristic zero. If $a_1, ..., a_n$ ($n>2$) are positive integers, the integral domain $B = k[X_1, ..., X_n] / ( X_1^{a_1} + ... + X_n^{a_n} )$ is called a Pham-Brieskorn ring. It is conjectured that if $a_i > 1$ for all $i$ and $a_i=2$ for at most one $i$, then $B$ is rigid. (A ring $B$ is said to be rigid if the only locally nilpotent derivation $D: B \to B$ is the zero derivation.) We give partial results towards the conjecture.

Cohomological rigidity for toric Fano manifolds of small dimensions or large Picard numbers

The cohomological rigidity problem for toric manifolds asks whether toric manifolds are diffeomorphic (or homeomorphic) if their integral cohomology rings are isomorphic. Many affirmative partial solutions to the problem have been obtained and no counterexample is known. In this paper, we study the diffeomorphism classification of toric Fano $d$-folds with $d=3,4$ or with Picard number $\ge 2d-2$. In particular, we show that those manifolds except for two toric Fano $4$-folds are diffeomorphic if their integral cohomology rings are isomorphic. The exceptional two toric Fano $4$-folds (their ID…