This paper addresses the problem of parametric model checking for weighted transition systems. We consider transition systems labelled with linear equations over a set of parameters and we use them to provide semantics for a parametric version of weighted CTL where the until and next operators are themselves indexed with linear equations. The parameters change the model-checking problem into a problem of computing a linear system of inequalities that characterizes the parameters that guarantee the satisfiability. To address this problem, we use parametric dependency graphs (PDGs) and we propose a global update function that yields an assignment to each node in a PDG. For an iterative application of the function, we prove that a fixed point assignment to PDG nodes exists and the set of assignments constitutes a well-quasi ordering, thus ensuring that the fixed point assignment can be found after finitely many iterations. To demonstrate the utility of our technique, we have implemented a prototype tool that computes the constraints on parameters for model checking problems.
@InProceedings{christoffersen_et_al:OASIcs.SynCoP.2015.77, author = {Christoffersen, Peter and Hansen, Mikkel and Mariegaard, Anders and Ringsmose, Julian Trier and Larsen, Kim Guldstrand and Mardare, Radu}, title = {{Parametric Verification of Weighted Systems}}, booktitle = {2nd International Workshop on Synthesis of Complex Parameters (SynCoP'15)}, pages = {77--90}, series = {Open Access Series in Informatics (OASIcs)}, ISBN = {978-3-939897-82-8}, ISSN = {2190-6807}, year = {2015}, volume = {44}, editor = {Andr\'{e}, \'{E}tienne and Frehse, Goran}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.SynCoP.2015.77}, URN = {urn:nbn:de:0030-drops-56115}, doi = {10.4230/OASIcs.SynCoP.2015.77}, annote = {Keywords: parametric weighted transition systems, parametric weighted CTL, parametric model checking, well-quasi ordering, tool} }
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