The modular hierarchy of the Toda lattice

Virasoro Symmetries of the Extended Toda Hierarchy

We prove that the extended Toda hierarchy of \cite{CDZ} admits nonabelian Lie algebra of infinitesimal symmetries isomorphic to the half of the Virasoro algebra. The generators $L_m$, $m\geq -1$ of the Lie algebra act by linear differential operators onto the tau function of the hierarchy. We also prove that the tau function of a generic solution to the extended Toda hierarchy is annihilated by a combination of the Virasoro operators and the flows of the hierarchy. As an application we show that the validity of the Virasoro constraints for the $CP^1$ Gromov-Witten invariants and their descende…

The Extended Bigraded Toda hierarchy

We generalize the Toda lattice hierarchy by considering N+M dependent variables. We construct roots and logarithms of the Lax operator which are uniquely defined operators with coefficients that are $ε$-series of differential polynomials in the dependent variables, and we use them to provide a Lax pair definition of the extended bigraded Toda hierarchy. Using R-matrix theory we give the bihamiltonian formulation of this hierarchy and we prove the existence of a tau function for its solutions. Finally we study the dispersionless limit and its connection with a class of Frobenius manifolds on th…

Infinite-dimensional Frobenius Manifolds Underlying the Toda Lattice Hierarchy

Following the approach of Carlet et al.(2011)\cite{CDM}, we construct a class of infinite-dimensional Frobenius manifolds underlying the Toda lattice hierarchy, which are defined on the space of pairs of meromorphic functions with possibly higher-order poles at the origin and at infinity. We also show a connection between these infinite-dimensional Frobenius manifolds and the finite-dimensional Frobenius manifolds on the orbit space of extended affine Weyl groups of type $A$ defined by Dubrovin and Zhang.

二维Toda层次$(n,1)$型有理约化的双哈密顿结构

Bihamiltonian structure of the $(n,1)$-type rational reductions of the 2D-Toda hierarchy

通过直接计算推导了$(n,1)$型二维Toda层次有理约化的局部双哈密顿结构，并构造了一个具有非平坦单位的$(n+1)$维半单广义Frobenius流形，其主层次包含无色散流。

2D-Toda层级的非对称有理约化与一类广义Frobenius流形

Asymmetric rational reductions of 2D-Toda hierarchy and a generalized Frobenius manifold

该研究分析了两类非对称2D-Toda层级有理约化的局部双哈密顿结构，构造了对应(2,1)型的三维广义Frobenius流形，并建立了其与双分次Toda、约束KP层级的变换关联。

Modular classes of Poisson-Nijenhuis Lie algebroids

The modular vector field of a Poisson-Nijenhuis Lie algebroid $A$ is defined and we prove that, in case of non-degeneracy, this vector field defines a hierarchy of bi-Hamiltonian $A$-vector fields. This hierarchy covers an integrable hierarchy on the base manifold, which may not have a Poisson-Nijenhuis structure.