Ribbon graphs and their invariants derived from quantum groups (Q1812912)

The authors construct the generalization of the Jones polynomial of links to the case of graphs in \(R^ 3\). They introduce the so-called coloured ribbon graphs in \(R^ 2 \times [0,1]\) and define for them Jones-type isotopy invariants. The approach to colouring is based on Drinfeld's notion of a quasitriangular Hopf algebra. For each quasitriangular Hopf algebra \(A\) the authors define \(A\)-coloured (ribbon) graphs. The colour of an edge is an \(A\)-module. The colour of a vertex is an \(A\)-linear homomorphism intertwining the modules which correspond to edges incident to this vertex. The category of an \(A\)-coloured ribbon graph is a compact braided strict monoidal category introduced by \textit{A. Joyal} and \textit{R. Street} [Braided monoidal categories, Macquarie Math. Reports, Report No. 860081 (1986)]. If \(A\) satisfies a minor additional condition, then the authors construct a canonical covariant functor from the category of \(A\)- coloured ribbon graphs into the category of \(A\)-modules. In the case of \(A\) being the quantized universal enveloping algebra of \(sl_ 2\) this functor generalizes the Jones polynomial of links. If \(A=U_ h(sl_ n(C))\) this generalizes the Jones-Conway (Thomflyp) polynomial and for \(A=U_ hG\), \(G=so(n)\), \(sp(2k)\) the Kauffman polynomial. The paper under review was followed by the authors' paper ``Invariants of 3-manifolds via link polynomials and quantum groups'' [Invent. Math. 103, 547-597 (1991; Zbl 0725.57007)]in which the authors construct new topological invariants of compact oriented manifolds (employing the methods of the paper under review). The construction was partially inspired by ideas of \textit{E. Witten} [Quantum field theory and the Jones polynomial, Commun. Math. Phys. 121, 351-399 (1989; Zbl 0667.57005)]who considered quantum field theory defined by the nonabelian Chern-Simon action and applied it to the study of 3-manifolds (on physical level of rigor).