Integrable Systems Seminar: Boll -- Multi-time Lagrangian 1-forms for families of Bäcklund transformations. Relativistic Toda-type systems

Dr Raphael Boll from the Technische Universität Berlin will give a talk on Thursday 21st
November at 4pm in Carslaw 829 (AGR).  All welcome! 

TITLE: Multi-time Lagrangian 1-forms for families of Bäcklund transformations.
Relativistic Toda-type systems 

ABSTRACT: We establish the pluri-Lagrangian structure for families of Bäcklund
transformations of relativistic Toda-type systems.  This is a generalization of the
results of our recent paper on non-relativistic Toda-type systems.  However, we present
an alternative approach to this theory using the pluri-Lagrangian structure of related
two-dimensional variational equations which we discussed in another recent paper.  Some
but not all of them have their origin in the Lagrangian structure of quad-equations.
Also in this situation, we have to deal with the multi-valuedness of the case of
periodic boundary conditions and again we describe the branching behavior by usage of
so-called superposition formulas.  The proofs of the closure relation are a more or less
direct consequence of the similar results of the related two-dimensional variational
equations.