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Computing steady-state distributions in infinite-state stochastic systems is in general a very difficult task. Product-form Petri nets are those Petri nets for which the steady-state distribution can be described as a natural product corresponding, up to a normalising constant, to an exponentiation of the markings. However, even though some classes of nets are known to have a product-form distribution, computing the normalising constant can be hard. The class of (closed) \Pi^3-nets has been proposed in an earlier work, for which it is shown that one can compute the steady-state distribution efficiently. However these nets are bounded. In this paper, we generalise queuing Markovian networks and closed \Pi^3-nets to obtain the class of open \Pi^3-nets, that generate infinite-state systems. We show interesting properties of these nets: (1) we prove that liveness can be decided in polynomial time, and that reachability in live \Pi^3-nets can be decided in polynomial time; (2) we show that we can decide ergodicity of such nets in polynomial time as well; (3) we provide a pseudo-polynomial time algorithm to compute the normalising constant.
@InProceedings{bouyer_et_al:LIPIcs.CONCUR.2017.31,
author = {Bouyer, Patricia and Haddad, Serge and Jug\'{e}, Vincent},
title = {{Unbounded Product-Form Petri Nets}},
booktitle = {28th International Conference on Concurrency Theory (CONCUR 2017)},
pages = {31:1--31:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-048-4},
ISSN = {1868-8969},
year = {2017},
volume = {85},
editor = {Meyer, Roland and Nestmann, Uwe},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2017.31},
URN = {urn:nbn:de:0030-drops-77957},
doi = {10.4230/LIPIcs.CONCUR.2017.31},
annote = {Keywords: Performance evaluation, infinite-state systems, Petri nets, steady-state distribution}
}