Mathematical modeling formalism for concurrent and distributed systems. Paweł Pokrywka uses Petri Nets as the underlying model to predict performance of distributed applications, and more generally proposes them as a fit for business logic more complicated than what a finite automaton can express. At wroclove.rb 2019 he released two Ruby gems built around Petri Nets: a performance-prediction tool and a lower-level gem for the Petri-Net model itself.