关于渐近上同调的消没性与Hausdorff性
On vanishing and Hausdorffness of asymptotic cohomology
- Instytut Matematyczny Polskiej Akademii Nauk(波兰科学院数学研究所)
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AI总结:
本文研究渐近上同调的消没性与Hausdorff性,证明了固定次数下消没等价于约化消没,并在一维一致凸情形下推出二维有界上同调的Hausdorff性。
AI中文摘要:
渐近上同调是最近引入的,用于研究群论中的稳定性问题。本文研究围绕渐近上同调的消没性与Hausdorff性问题。我们的第一个主要结果是,在固定次数和固定渐近系数模下,渐近上同调的消没等价于约化渐近上同调的消没。在对角系数模的特殊情形下,我们还获得了用有界上同调表示的消没性的完整刻画。我们的第二个主要结果是,对于一致凸渐近Banach模,渐近上同调在次数1消没。由此,在相同的一致凸性假设下,我们可以推出次数2的有界上同调的Hausdorff性。
英文摘要:
Asymptotic cohomology was recently introduced to study stability problems in group theory. This paper studies vanishing and Hausdorffness questions around asymptotic cohomology. Our first main result is that, in a fixed degree and for a fixed asymptotic coefficient module, vanishing of asymptotic cohomology is equivalent to vanishing of reduced asymptotic cohomology. In the special case of diagonal coefficient modules, we also obtain a full characterisation of vanishing in terms of bounded cohomology. Our second main result is that asymptotic cohomology vanishes in degree 1 for uniformly convex asymptotic Banach modules. From this, we can deduce Hausdorffness of degree-2 bounded cohomology under the same uniform convexity assumption.