Skein modules

Abstract

We describe in this chapter (Chapter IX) the idea of building an algebraic topology based on knots (or more generally on the position of embedded objects). That is, our basic building blocks are considered up to ambient isotopy (not homotopy or homology). For example, one should start from knots in 3-manifolds, surfaces in 4-manifolds, etc. However our theory is, until now, developed only in the case of links in 3-manifolds, with only a glance towards 4-manifolds. The main object of the theory is a skein module and we devote this chapter mostly to the description of skein modules in 3-dimensional manifolds. H. Poincare, in his paper "Analysis situs" (1895), abstractly defined homology groups starting from formal linear combinations of simplices, choosing cycles and dividing them by relations coming from boundaries The idea behind skein modules is to use links instead of cycles (in the case of a 3-manifold). More precisely we consider the free module generated by links modulo properly chosen (local) skein relations.