On multiplicity-free weight modules over quantum affine algebras

Our goal is to construct and study the multiplicity-free weight modules of quantum affine algebras.For this, we introduce the notion of shiftability condition with respect to a symmetrizable generalized Cartan matrix, and investigate its applications on the study of quantum affine algebra structures and the realizations of the infinite-dimensional multiplicity-free weight modules.We also compute the highest `-weights of the infinite-dimensional multiplicity-free weight modules as highest `-weight modules.