Permutations, isotropy and smooth cyclic group actions on definite 4-manifolds

具有非循环基本群的奇异定四维流形

Exotic definite four-manifolds with non-cyclic fundamental group

本文在基本群为 $\mathbb{Z}/2\times \mathbb{Z}/2$ 的定四维流形上构造了无穷多个两两非微分同胚的光滑结构，揭示了该流形上光滑结构的丰富性。

Splitting criteria for a definite 4-manifold with infinite cyclic fundamental group

Two criteria for a closed connected definite 4-manifold with infinite cyclic fundamental group to be TOP-split are given. One criterion extends a sufficient condition made in a previous paper. The result is equivalent to a purely algebraic result on the question asking when a positive definite Hermitian form over the ring of integral one-variable Laurent polynomials is represented by an integer matrix. As an application, an infinite family of orthogonally indecomposable unimodular odd definite symmetric $Z$-forms is produced.

有限循环作用在正定$4$-流形上的权重

Weights of finite cyclic actions on definite $4$-manifolds

本文用等变Seiberg–Witten理论重新证明了正定4-流形上有限循环群作用的不动点集和切向表示与线性作用的等变连通和一致，并确定了所有等变线丛的权重。

4-流形上的有限群作用与等变丛

Finite group actions on 4-manifolds and equivariant bundles

本研究针对具有同调平凡局部线性循环群作用的4-流形，通过扭曲符号公式推导得出等变丛存在的充要条件，该条件体现为不动点数据与迷向表示间的同余关系。

On definite strongly quasipositive links and L-space branched covers

We investigate the problem of characterising the family of strongly quasipositive links which have definite symmetrised Seifert forms and apply our results to the problem of determining when such a link can have an L-space cyclic branched cover. In particular, we show that if $δ_n = σ_1 σ_2 \ldots σ_{n-1}$ is the dual Garside element and $b = δ_n^k P \in B_n$ is a strongly quasipositive braid whose braid closure $\widehat b$ is definite, then $k \geq 2$ implies that $\widehat b$ is one of the torus links $T(2, q), T(3,4), T(3,5)$ or pretzel links $P(-2, 2, m), P(-2,3,4)$. Applying Theorem 1.1 …

Periodic maps of composite order on positive definite 4-manifolds

The possibilities for new or unusual kinds of topological, locally linear periodic maps of non-prime order on closed, simply connected 4-manifolds with positive definite intersection pairings are explored. On the one hand, certain permutation representations on homology are ruled out under appropriate hypotheses. On the other hand, an interesting homologically nontrivial, pseudofree, action of the cyclic group of order 25 on a connected sum of ten copies of the complex projective plane is constructed.