Singular \(R\)-matrices and Drinfeld's comultiplication (Q1364200)

The author computes the \(R\)-matrix which interwines two-dimensional evaluation representations with Drinfeld's comultiplication on \(U_q(\widehat{sl}_2)\). The algebra \(A(R)\) is generated with relations determined by \(R\). In the category of highest-weight representations, there is a Hopf algebra isomorphism between \(A(R)\) and an extension of \(U_q(\widehat{sl}_2)\).