  We propose a variant of the CCS process algebra with new features aiming at
allowing multiscale modelling of biological systems. In the usual semantics of
process algebras for modelling biological systems actions are instantaneous.
When different scale levels of biological systems are considered in a single
model, one should take into account that actions at a level may take much more
time than actions at a lower level. Moreover, it might happen that while a
component is involved in one long lasting high level action, it is involved
also in several faster lower level actions. Hence, we propose a process algebra
with operations and with a semantics aimed at dealing with these aspects of
multiscale modelling. We study behavioural equivalences for such an algebra and
give some examples.
