Norbert Schappacher (Strasbourg), Marie-Françoise Roy (Rennes)
We define sets with independence relations which are a generalisation of locality in physics. An example of such relation is given on the set of multivariable functions. A coproduct respecting the independence relations allows to define a multivariable renormalisation scheme. We show that the Birkhoff decomposition then simplifies, allowing to facilitate rationality proof.