  We propose PALPS, a Process Algebra with Locations for Population Systems.
PALPS allows us to produce spatially-explicit, individual-based models and to
reason about their behavior. Our calculus has two levels: at the first level we
may define the behavior of an individual of a population while, at the second
level, we may specify a system as the collection of individuals of various
species located in space, moving through their life cycle while changing their
location, if they so wish, and interacting with each other in various ways such
as preying on each other. Furthermore, we propose a probabilistic temporal
logic for reasoning about the behavior of PALPS processes. We illustrate our
framework via models of dispersal in metapopulations.
