The contribution The Reachability Problem for Petri Nets is Not Elementary by Wojciech Czerwinski, Slawomir Lasota, Ranko Lazic, Jerome Leroux and Filip Mazowiecki has won a Best Paper Award at the 51st Annual ACM Symposium on the Theory of Computing, to be held on June 23-26, 2019 in Phoenix, AZ.

This work, which was supported by a Leverhulme Research Fellowship, shows that the central verification problem for Petri nets is much harder than has been known since the landmark result of Richard Lipton in 1976. Petri nets, also known as vector addition systems, are a long established model of concurrency with extensive applications in modelling and analysis of hardware, software and database systems, as well as chemical, biological and business processes.