Atkinson, James (2008) Integrable lattice equations: connection to the Möbius group, Bäcklund transformations and solutions. PhD thesis, University of Leeds.

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Abstract
We consider scalar integrable lattice equations which arise as the natural discrete counterparts to KdVtype PDEs. Several results are reported. We identify a new and natural connection between the ‘Schwarzian’ (Möbius invariant) integrable lattice systems and the Möbius group itself. The lattice equation in some sense describes dynamics of fixedpoints as they change under composition between transformations. A classification result is given for lattice equations which are linear but also consistent on the cube. Such systems lie outside previous classification schemes. New Bäcklund transformations (BTs) for some known integrable lattice equations are given. As opposed to the natural autoBT inherent in every such equation, these BTs are of two other kinds. Specifically, it is found that some equations admit additional autoBTs (with Bäcklund parameter), whilst some pairs of apparently distinct equations admit a BT which connects them. Adler’s equation has come to hold the status of ‘master equation’ among the integrable lattice equations. Solutions of this equation are derived which are associated with 1cycles and 2cycles of the BT. They were the first explicit solutions written for Adler’s equation. We also apply the BT to the 1cycle solution in order to construct a solitontype solution.
Item Type:  Thesis (PhD) 

Keywords:  Integrable systems, discrete, lattice equation, Backlund transformation, Soliton 
Academic Units:  The University of Leeds > Faculty of Maths and Physical Sciences (Leeds) > School of Mathematics (Leeds) The University of Leeds > Faculty of Maths and Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds) 
Identification Number/EthosID:  uk.bl.ethos.502791 
Depositing User:  Dr James Atkinson 
Date Deposited:  01 Jun 2015 09:08 
Last Modified:  25 Nov 2015 13:26 
URI:  http://etheses.whiterose.ac.uk/id/eprint/9081 