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arXiv 2107.05048math.DGmath.CV
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殆Hermitian流形上的Bott-Chern Laplacian算子

Bott-Chern Laplacian on almost Hermitian manifolds

Riccardo Piovani, Adriano Tomassini

摘要:

设$(M,J,g,ω)$是一个$2n$维几乎厄米流形.本文推广了$(M,J,g,ω)$上Bott-Chern Laplacian的定义,证明了它仍然是椭圆的.在紧致凯勒流形上,Dolbeault Laplacian和Bott-Chern Laplacian的核重合。当$(M,J,g,ω)$是紧的几乎Kähler流形时,我们证明了这样的性质不成立,从而在Kodaira-Thurston流形上提供了一个明确的几乎Kähler结构。进一步,如果$(M,J,g,ω)$是连通紧几乎Hermitian $4$ -流形,用$h^{1,1}_{BC}$表示Bott-Chern调和$(1,1)$ -形式空间的维数,我们证明了$h^{1,1}_{BC}=b^-$或$h^{1,1}_{BC}=b^-+1$ .特别地,如果$g$几乎是Kähler,那么就有$h^{1,1}_{BC}=b^-+1$,推广了Holt和Zhang关于Dolbeault Laplacian核的结果.我们还证明了Bott-Chern和Dolbeault调和$(1,1)$ -形式空间的维数在具有严格局部共形几乎Kähler度量的几乎复4-流形上的行为是不同的。最后,我们将一些空间的Bott-Chern调和形式的Bott-Chern上同调群的殆复流形,最近推出的Coelho,Placini和Stelzig。

英文摘要:

Let $(M,J,g,ω)$ be a $2n$-dimensional almost Hermitian manifold. We extend the definition of the Bott-Chern Laplacian on $(M,J,g,ω)$, proving that it is still elliptic. On a compact Kähler manifold, the kernels of the Dolbeault Laplacian and of the Bott-Chern Laplacian coincide. We show that such a property does not hold when $(M,J,g,ω)$ is a compact almost Kähler manifold, providing an explicit almost Kähler structure on the Kodaira-Thurston manifold. Furthermore, if $(M,J,g,ω)$ is a connected compact almost Hermitian $4$-manifold, denoting by $h^{1,1}_{BC}$ the dimension of the space of Bott-Chern harmonic $(1,1)$-forms, we prove that either $h^{1,1}_{BC}=b^-$ or $h^{1,1}_{BC}=b^-+1$. In particular, if $g$ is almost Kähler, then $h^{1,1}_{BC}=b^-+1$, extending the result by Holt and Zhang for the kernel of Dolbeault Laplacian. We also show that the dimensions of the spaces of Bott-Chern and Dolbeault harmonic $(1,1)$-forms behave differently on almost complex 4-manifolds endowed with strictly locally conformally almost Kähler metrics. Finally, we relate some spaces of Bott-Chern harmonic forms to the Bott-Chern cohomology groups for almost complex manifolds, recently introduced by Coelho, Placini and Stelzig.

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