The aim of this volume that presents lectures given at a joint CIME and
Banach Center Summer School, is to offer a broad presentation of a class
of updated methods providing a mathematical framework for the
development of a hierarchy of models of complex systems in the natural
sciences, with a special attention to biology and medicine. Mastering
complexity implies sharing different tools requiring much higher level
of communication between different mathematical and scientific schools,
for solving classes of problems of the same nature. Today more than
ever, one of the most important challenges derives from the need to
bridge parts of a system evolving at different time and space scales,
especially with respect to computational affordability. As a result the
content has a rather general character; the main role is played by
stochastic processes, positive semigroups, asymptotic analysis, kinetic
theory, continuum theory, and game theory.