Idempotent biquadratics, Yang-Baxter maps and birational representations of Coxeter groups

2013/01/20 by James Atkinson, Atkinson, James
Mathematics · Physics and Astronomy · #Exactly Solvable and Integrable Systems (nlin.SI) #FOS: Physical sciences #Mathematical Physics (math-ph) #math-ph #math.MP #nlin.SI

paper · pdf · doi:10.48550/arxiv.1301.4613

40 pages, 9 figures, 2 tables

arxiv created 2013/12/22 · arxiv updated 2013/12/24

Abstract

A transformation is obtained which completes the unification of quadrirational Yang-Baxter maps and known integrable multi-quadratic quad equations. By combining theory from these two classes of quad-graph models we find an extension of the known integrability feature, and show how this leads subsequently to a natural extension of the associated lattice geometry. The extended lattice is encoded in a birational representation of a particular sequence of Coxeter groups. In this setting the usual quad-graph is associated with a subgroup of type BC_n, and is part of a larger and more symmetric ambient space. The model also defines, for instance, integrable dynamics on a triangle-graph associated with a subgroup of type A_n, as well as finite degree-of-freedom dynamics, in the simplest cases associated with affine-E6 and affine-E8 subgroups. Underlying this structure is a class of biquadratic polynomials, that we call idempotent, which express the trisection of elliptic function periods algebraically via the addition law.

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