In: Algebra, Combinatorics and Logic in Computer Sience, Conf. Proceedings, Gyoer (Hungaria), Vol. 1, pages 87-96. 1986.
Abstract: In this paper a connection between the class of certain Petri net languages (accepted by so called basic Petri nets) with the class of prefix-free languages is investigated. The class of languages accepted by basic Petri nets is closed under some usual and some unusual operations.