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arXiv · 1509.02592

The asymptotic behavior of Frobenius direct images of rings of invariants

Mitsuyasu Hashimoto·Peter Symonds
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Abstract

We define the Frobenius limit of a module over a ring of prime characteristic to be the limit of the normalized Frobenius direct images in a certain Grothendieck group. When a finite group acts on a polynomial ring, we calculate this limit for all the modules over the twisted group algebra that are free over the polynomial ring; we also calculate the Frobenius limit for the restriction of these to the ring of invariants. As an application, we generalize the description of the generalized $F$-signature of a ring of invariants by the second author and Nakajima to the modular case.

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Mitsuyasu Hashimoto, Peter Symonds. 2015-09-09. The asymptotic behavior of Frobenius direct images of rings of invariants. https://arxiv.org/abs/1509.02592

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