離散数理モデリングセミナー

過去の記録 ~10/23次回の予定今後の予定 10/24~

担当者 時弘哲治, ウィロックス ラルフ

次回の予定

2021年10月28日(木)

19:00-20:00   オンライン開催
Zoomを用いてオンラインで行います.参加希望の方はウィロックスまでZoomのリンクをお尋ねください.
Andrew Hone 氏 (University of Kent)
Deformations of cluster mutations and invariant presymplectic forms
[ 講演概要 ]
We consider deformations of sequences of cluster mutations in finite type cluster algebras, which destroy the Laurent property but preserve the presymplectic structure defined by the exchange matrix. The simplest example is the Lyness 5-cycle, arising from the cluster algebra of type A_2: this deforms to the Lyness family of integrable symplectic maps in the plane. For types A_3 and A_4 we find suitable conditions such that the deformation produces a two-parameter family of Liouville integrable maps (in dimensions two and four, respectively). We also perform Laurentification for these maps, by lifting them to a higher-dimensional space of tau functions with a cluster algebra structure, where the Laurent property is restored. More general types of deformed mutations associated with affine Dynkin quivers are shown to correspond to four-dimensional symplectic maps arising as reductions of the discrete sine-Gordon equation.