  We discuss a method to describe the qualitative dynamics of chemical reaction
networks in terms of symbolic dynamics. The method, that can be applied to
mass-action reaction networks with separated timescales, uses solutions of the
partial tropical equilibration problem as proxies for symbolic states. The
partial tropical equilibration solutions are found algorithmically. These
solutions also provide the scaling needed for slow-fast decomposition and model
reduction. Any trace of the model can thus be represented as a sequence of
local approximations of the full model. We illustrate the method using as case
study a biochemical model of the cell cycle.
