  Algorithms for the symbolic computation of conserved densities, fluxes,
generalized symmetries, and recursion operators for systems of nonlinear
differential-difference equations are presented. In the algorithms we use
discrete versions of the Frechet and variational derivatives, as well as
discrete Euler and homotopy operators.
  The algorithms are illustrated for prototypical nonlinear lattices, including
the Kac-van Moerbeke (Volterra) and Toda lattices. Results are shown for the
modified Volterra and Ablowitz-Ladik lattices.
