Integrable systems with impurity
  After reviewing some basic properties of RT algebras, which appear to be the natural framework to deal with integrable systems in presence of an impurity, we show how any integrable system (including these possessing translation invariance) can be promoted to an integrable system with an impurity which can reflect and transmit particles. The technics allows bulk translation invariant $S$-matrices while avoiding the no-go theorem stated recently about these laters.   Presented at the Vth International workshop on Lie theory and its applications in physics, Varna (Bulgaria), June 16-22, 2003 
E. Ragoucy