Truncation of functional relations in the XXZ model
  This is the abstract of the revised paper. The integrable XXZ model with a special open boundary condition is considered. We study Sklyanin transfer matrices after quantum group reduction in roots of unity. In this case Sklyanin transfer matrices satisfy a closed system of truncated functional equations. The algebraic reason for the truncation is found.The important role in proving of the result is performed by Zamolodchikov algebra introduced in the paper. 
A. A. Belavin, S. Yu. Gubanov, B. L. Feigin