On integrable quantum group invariant antiferromagnets

10 pages, 7 figures.-- PACS nrs.: 05.50.+q, 02.90.+p, 75.10.Jm.-- MSC1991 codes: 82B23, 17B37.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-th/9205109Lecture given by C.G. at the Winter School on Theoretical Physics, Wroclaw, Poland, February 1992.MR#: MR1230443 (94d:81071)^aA new open spin chain hamiltonian is introduced. It is both integrable (Sklyanin's type K matrices are used to achieve this) and invariant under Uε(sl(2)) transformations in nilpotent irreps for ε^3 = 1. Some considerations on the centralizer of nilpotent representations and its representation theory are also presented.First author (R.C.) was supported by a PFPI grant of the Spanish MEC.Publicad