Abstract
Models of biological systems expressed as multiset rewriting systems can be very complex, impeding the analysis of their behaviour. In this paper we propose a practical solution to this problem, in the form of change monitors, i.e. computational instruments which synchronise with the model and record its behaviour. Change monitors play the role of passive observers. Since change monitors can automatically identify specific behaviours generated by the model under investigation, it is sufficient to focus only on the output produced by the monitors (instead of examining the dynamics of the initial model).