Non-Abelian symmetries of the half-infinite XXZ spin chain.

The non-Abelian symmetries of the half-infinite XXZ spin chain for all possible types of integrable boundary conditions are classified. For each type of boundary conditions, an analog of the Chevalley-type presentation is given for the corresponding symmetry algebra. In particular, two new algebras arise that are, respectively, generated by the symmetry operators of the model with triangular and special U q ( g l 2 ) -invariant integrable boundary conditions. [ABSTRACT FROM AUTHOR]