  Biological systems are typically very complex and need to be reduced before
they are amenable to a thorough analysis. Also, they often possess functionally
important dynamic features like bistability. In model reduction, it is
sometimes more desirable to preserve the dynamic features only than to recover
a good quantitative approximation. We present an approach to reduce the order
of a bistable dynamical system significantly while preserving bistability and
the switching threshold. These properties are important for the operation of
the system in the context of a larger network. As an application example, a
bistable model for caspase activation in apoptosis is considered.
