Abstract
The assumption of perfect knowledge of rate parameters in continuous-time Markov chains (CTMCs) is undermined when confronted with reality, where they may be uncertain due to lack of information or because of measurement noise. In this paper we consider uncertain CTMCs, where rates are assumed to vary non-deterministically with time from bounded continuous intervals. This leads to a semantics which associates each state with the reachable set of its probability under all possible choices of the uncertain rates. We develop a notion of lumpability which identifies a partition of states where each block preserves the reachable set of the sum of its probabilities, essentially lifting the well-known CTMC ordinary lumpability to the uncertain setting. We proceed with this analogy with two further contributions: a logical characterization of uncertain CTMC lumping in terms of continuous stochastic logic; and a polynomial time and space algorithm for the minimization of uncertain CTMCs by partition refinement, using the CTMC lumping algorithm as an inner step. As a case study, we show that the minimizations in a substantial number of CTMC models reported in the literature are robust with respect to uncertainties around their original, fixed, rate values.
| Original language | English |
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| Title of host publication | Quantitative Evaluation of Systems |
| Editors | Alessandro Abate, Andrea Marin |
| Publisher | Springer |
| Publication date | 2021 |
| Pages | 391-409 |
| ISBN (Print) | 9783030851712 |
| DOIs | |
| Publication status | Published - 2021 |
| Event | 18th International Conference on Quantitative Evaluation of Systems - Virtual, Online Duration: 23 Aug 2021 → 27 Aug 2021 https://www.qest.org/qest2021/ |
Conference
| Conference | 18th International Conference on Quantitative Evaluation of Systems |
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| City | Virtual, Online |
| Period | 23/08/2021 → 27/08/2021 |
| Internet address |
| Series | Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) |
|---|---|
| Volume | 12846 LNCS |
| ISSN | 0302-9743 |
Bibliographical note
Funding Information:Acknowledgement. Luca Cardelli is supported by a Royal Society Research Professorship. The work has been partially supported by the ERC Advanced Grant LASSO, the Villum Investigator Grant S4OS, the EU-Ecsel project iDev40, the FFG project Adex, the PRIN project SEDUCE, no. 2017TWRCNB, the FWF project COCO no. M-2393-N32, the Poul Due Jensen Foundation grant no. 883901, and by the DFF RP1 project REDUCTO no. 9040-00224B.
Publisher Copyright:
© 2021, Springer Nature Switzerland AG.