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arXiv · 2106.14796

The earliest diamond of finite type in Nottingham algebras

Marina Avitabile·Sandro Mattarei
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Abstract

We prove several structural results on Nottingham algebras, a class of infinite-dimensional, modular, graded Lie algebras, which includes the graded Lie algebra associated to the Nottingham group with respect to its lower central series. Homogeneous components of a Nottingham algebra have dimension one or two, and in the latter case they are called diamonds. The first diamond occurs in degree $1$, and the second occurs in degree $q$, a power of the characteristic. Each diamond past the second is assigned a type, which either belongs to the underlying field or is $\infty$. Nottingham algebras with a variety of diamond patterns are known. In particular, some have diamonds of both finite and infinite type. We prove that each of those known examples is uniquely determined by a certain finite-dimensional quotient. Finally, we determine how many diamonds of type $\infty$ may precede the earliest diamond of finite type in an arbitrary Nottingham algebra.

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Marina Avitabile, Sandro Mattarei. 2021-06-28. The earliest diamond of finite type in Nottingham algebras. https://arxiv.org/abs/2106.14796

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