We construct a factorizing Drinfel'd twist for a face type model equivalent to the XYZ model. Completely symmetric expressions for the operators of the monodromy matrix are obtained.
We construct Drinfel'd twists for the rational sl ( n ) XXX model giving rise to a completely symmetric representation of the monodromy matrix. We obtain a polarization-free representation of the pseudoparticle creation operators figuring in the construction of the Bethe vectors within the framework of the quantum inverse scattering method. This representation enables us to resolve the hierarchy of the nested Bethe ansatz for the sl ( n ) invariant rational Heisenberg model. Our results generalize the findings of Maillet and Sanchez de Santos for sl (2) models.