Poisson brackets of mappings obtained as (q,-p) reductions of lattice   equations
  In this paper, we present Poisson brackets of certain classes of mappings obtained as general periodic reductions of integrable lattice equations. The Poisson brackets are derived using the so called Ostrogradsky transformation. 
Dinh T. Tran, Peter H. van der Kamp and G. Reinout W. Quispel
nlin.SI