Symmetric Monoidal Categories in Chemistry and Biology

John Baez – 8 February 2012

Chemists use "chemical reaction networks" to describe interactions between things of different types. In population biology and the study of infectious diseases, "stochastic Petri nets" are sometimes used for the same purpose. In fact chemical reaction networks and stochastic Petri nets are essentially the same thing. The theory of symmetric monoidal categories can help us understand what this thing is, and how to work with it.