Parallelism and Synchronization in an Infinitary Context

We study multitoken interaction machines in the context of a very expressive linear logical system with exponentials, fix points and synchronization. The advantage of such machines is to provide models in the style of the Geometry of Interaction, i.e., An interactive semantics which is close to low-level implementation. On the one hand, we prove that despite the inherent complexity of the framework, interaction is guaranteed to be deadlock-free. On the other hand, the resulting logical system is powerful enough to embed PCF and to adequately model its behaviour, both when call-by-name and when call-by-value evaluation are considered. This is not the case for single-token stateless interactive machines.