Francesco Basile Pasquale Chiacchio Alessandro Giua Suboptimal supervisory control of Petri nets in presence of uncontrollable transitions via monitor places. 995-1004 2006 42 Automatica 6 http://dx.doi.org/10.1016/j.automatica.2006.02.003 db/journals/automatica/automatica42.html#BasileCG06