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Discrete mathematical modelling seminar
Seminar information archive ～05/01｜Next seminar｜Future seminars 05/02～
| Organizer(s) | Tetsuji Tokihiro, Ralph Willox |
|---|
2025/02/20
16:00-17:30 Room #126 (Graduate School of Math. Sci. Bldg.)
Andy Hone (University of Kent)
Integrable maps associated with Stieltjes fractions and the Volterra lattice
Andy Hone (University of Kent)
Integrable maps associated with Stieltjes fractions and the Volterra lattice
[ Abstract ]
Quite recently, a classification of birational maps in 4D that have a Lagrangian structure and are Liouville integrable was derived by Gubbiotti, building on earlier results obtained with Joshi, Tran and Viallet. Here we show that the first member in this family naturally arises from the Stieltjes continued fraction expansion of a meromorphic function on a genus 2 curve, and is associated with special solutions of the Volterra lattice hierarchy. This construction extends to hyperelliptic curves of all genera, producing a family of Poisson maps on an affine space of Lax matrices, with explicit Hankel determinant expressions for the tau functions. In particular, in the genus 1 case one finds elliptic solutions of the Volterra lattice, obtained from a QRT map whose tau functions satisfy the Somos-5 relation. We also observe that the other 4D maps in Gubbiotti's classification correspond to genus 2 solutions of two distinct forms of the modified Voltera lattice. If time permits, we will also mention the connection with families of orthogonal polynomials. This is joint work with John Roberts, Pol Vanhaecke and Federico Zullo.
Quite recently, a classification of birational maps in 4D that have a Lagrangian structure and are Liouville integrable was derived by Gubbiotti, building on earlier results obtained with Joshi, Tran and Viallet. Here we show that the first member in this family naturally arises from the Stieltjes continued fraction expansion of a meromorphic function on a genus 2 curve, and is associated with special solutions of the Volterra lattice hierarchy. This construction extends to hyperelliptic curves of all genera, producing a family of Poisson maps on an affine space of Lax matrices, with explicit Hankel determinant expressions for the tau functions. In particular, in the genus 1 case one finds elliptic solutions of the Volterra lattice, obtained from a QRT map whose tau functions satisfy the Somos-5 relation. We also observe that the other 4D maps in Gubbiotti's classification correspond to genus 2 solutions of two distinct forms of the modified Voltera lattice. If time permits, we will also mention the connection with families of orthogonal polynomials. This is joint work with John Roberts, Pol Vanhaecke and Federico Zullo.
