Q-characters of the tensor products
  Let $\pi_1,...,\pi_n$ be an irreducible finite-dimensional $\mathfrak{sl}_2$-modules. Using the theory of the representations of the current algebras, we introduce a several ways to construct a $q$-grading on $\pi_1\otimes...\otimes\pi_n$. We study the corresponding graded modules and prove, that they are essentially the same. 
B.Feigin and E.Feigin