@article{Aceto_Fokkink_Ingólfsdóttir_2002, title={A Note on an Expressiveness Hierarchy for Multi-exit Iteration}, volume={9}, url={https://tidsskrift.dk/brics/article/view/21755}, DOI={10.7146/brics.v9i40.21755}, abstractNote={Multi-exit iteration is a generalization of the standard binary Kleene star operation that allows for the specification of agents that, up to bisimulation equivalence, are solutions of systems of recursion equations of the form<br />X_1 = P_1 X_2 + Q_1 <br /><br /> X_n = P_n X_1 + Q_n <br /><br /> where n is a positive integer, and the P_i and the Q_i are process terms. The addition of multi-exit iteration to Basic Process Algebra (BPA) yields a more expressive language than that obtained by augmenting BPA with the standard binary Kleene star. This note offers an expressiveness hierarchy, modulo bisimulation equivalence, for the family of multi-exit iteration operators proposed by Bergstra, Bethke and Ponse.}, number={40}, journal={BRICS Report Series}, author={Aceto, Luca and Fokkink, Willem Jan and Ingólfsdóttir, Anna}, year={2002}, month={Sep.} }