A note on the complexity of finding and enumerating elementary modes

In the context of the study into elementary modes of metabolic networks, we prove two complexity results. Enumerating elementary modes containing a specific reaction is hard in an enumeration complexity sense. The decision problem if there exists an elementary mode containing two specific reactions is NP-complete. The complexity of enumerating all elementary modes remains open. (C) 2009 Elsevier Ireland Ltd. All rights reserved.