# Computing + Mathematical Sciences Seminar

Wednesday
October 30, 2013
4:00 PM

**Petri nets, chemistry, and quantum theory**

**Speaker:**John Baez, Department of Mathematics, University of California - Riverside

**Location:**Annenberg 105

Chemists use "chemical reaction networks" to describe random interactions between things of different types. These are essentially the same as what computer scientists call "Petri nets", or mathematicians would call "free symmetric monoidal categories". The reachability problem for a Petri net asks which collections of things can turn into which other collections of things: it is decidable but hard. More relevant to chemistry is the master equation, a differential equation describing how the probability that some collection will turn into some other collection changes with time. This turns out to have a nice description using some math from quantum field theory, but with probabilities replacing amplitudes.
Refreshments at 3:45pm in 106 Annenberg

**Series**Computing + Mathematical Sciences Lecture Series

**Contact:** Lucinda Acosta at 4843 lucinda@caltech.edu