Some phenomena in tautological rings of manifolds

Oscar Randal-Williams

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arXiv · 1611.03038

Some phenomena in tautological rings of manifolds

Oscar Randal-Williams

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Abstract

We prove several basic ring-theoretic results about tautological rings of manifolds W, that is, the rings of generalised Miller--Morita--Mumford classes for fibre bundles with fibre W. Firstly we provide conditions on the rational cohomology of W which ensure that its tautological ring is finitely-generated, and we show that these conditions cannot be completely relaxed by giving an example of a tautological ring which fails to be finitely-generated in quite a strong sense. Secondly, we provide conditions on torus actions on W which ensure that the rank of the torus gives a lower bound for the Krull dimension of the tautological ring of W. Lastly, we give extensive computations in the tautological rings of CP^2 and S^2 x S^2.

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Oscar Randal-Williams. 2016-11-09. Some phenomena in tautological rings of manifolds. https://arxiv.org/abs/1611.03038

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