We propose a systematic approach to approximate the behavior of models of polymers synthesis/degradation, described in Kappa. Our abstraction consists in focusing on the behavior of all the patterns of size less than a given parameter. We infer symbolic equalities and inequalities which intentionally may be understood as algebraic constructions over patterns, and extensionally as sound properties about the concentration of the bio-molecular species that contain these patterns. Then, we derive a system of equations describing the time evolution of a lower and an upper bounds for the concentration of each pattern of interest.
