  The S-pi-calculus is a synchronous pi-calculus which is based on the SL
model. The latter is a relaxation of the Esterel model where the reaction to
the absence of a signal within an instant can only happen at the next instant.
In the present work, we present and characterise a compositional semantics of
the S-pi-calculus based on suitable notions of labelled transition system and
bisimulation. Based on this semantic framework, we explore the notion of
determinacy and the related one of (local) confluence.
