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arXiv · 2111.10905

Casting light on shadow Somos sequences

Andrew N. W. Hone
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Abstract

Recently Ovsienko and Tabachnikov considered extensions of Somos and Gale-Robinson sequences, defined over the algebra of dual numbers. Ovsienko used the same idea to construct so-called shadow sequences derived from other nonlinear recurrence relations exhibiting the Laurent phenomenon, with the original motivation being the hope that these examples should lead to an appropriate notion of a cluster superalgebra, incorporating Grassmann variables. Here we present various explicit expressions for the shadow of Somos-4 sequences, and describe the solution of a general Somos-4 recurrence defined over the $\mathbb{C}$-algebra of dual numbers from several different viewpoints: analytic formulae in terms of elliptic functions, linear difference equations, and Hankel determinants.

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Andrew N. W. Hone. 2021-11-21. Casting light on shadow Somos sequences. https://arxiv.org/abs/2111.10905

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