An Approach to Master Symmetries of Lattice Equations
  An approach to master symmetries of lattice equations is proposed by the use of discrete zero curvature equation. Its key is to generate non-isospectral flows from the discrete spectral problem associated with a given lattice equation. A Volterra-type lattice hierarchy and the Toda lattice hierarchy are analyzed as two illustrative examples. 
Benno Fuchssteiner and Wen-Xiu Ma