38 D. Lepri, E. Ábrahám, and P. Cs. Ölveczky Us<strong>in</strong>g the gcd strategy we can also determ<strong>in</strong>e a “m<strong>in</strong>imal” time <strong>in</strong>terval such that the above bounded response is satisfied <strong>in</strong> the system. In particular, we discovered that this <strong>in</strong>terval is [5, 12] by try<strong>in</strong>g different values for a and b <strong>in</strong> the <strong>in</strong>terval-bounded command Maude> (mc-tctl {<strong>in</strong>it} |= AG((’HierarchicalTrafficLight . ’Decision | (port ’Error is present)) implies AF[c a, b c] (’HierarchicalTrafficLight | (’Cyel = # 1, ’Cgrn = # 0, ’Cred = # 0)))) .) Figure 8 shows the dialog w<strong>in</strong>dow for the <strong>Real</strong>-<strong>Time</strong> Maude code generation of the hierarchical traffic light model: after enter<strong>in</strong>g the error handl<strong>in</strong>g property, a simple click on the Generate button will display the result of the model check<strong>in</strong>g command execution <strong>in</strong> the “Code Generator Commands” box. 7 Conclusions and Future Work We have described the semantic foundations of our T<strong>CTL</strong> model checker for <strong>Real</strong>-<strong>Time</strong> Maude. Our model<strong>in</strong>g formalism is more expressive than those of other timed model checkers, allow<strong>in</strong>g us to analyze real-time systems which are beyond the scope of other verification tools. In particular, we have proved soundness and completeness of our model checker for a class of dense-time <strong>Real</strong> <strong>Time</strong> Maude specifications that conta<strong>in</strong> many systems outside the scope of other real-time model checkers. Furthermore, the <strong>in</strong>troduced T<strong>CTL</strong> model checker also provides for free a timed temporal logic model checker for <strong>in</strong>terest<strong>in</strong>g subsets of model<strong>in</strong>g languages widely used <strong>in</strong> <strong>in</strong>dustry, such as Ptolemy II and the avionics standard AADL. So far, we have only proved soundness and completeness for formulas with closed <strong>in</strong>tervals under the cont<strong>in</strong>uous semantics. We should also cover formulas with open time <strong>in</strong>tervals and the po<strong>in</strong>twise semantics. The model checker should also provide counter-examples <strong>in</strong> a user-friendly way, when possible. We should also extend our model checker to time-bounded T<strong>CTL</strong> model check<strong>in</strong>g to support the model check<strong>in</strong>g of systems with <strong>in</strong>f<strong>in</strong>ite reachable state space. F<strong>in</strong>ally, the current version of the tool is implemented at the Maude meta-level; for efficiency purposes, it should be implemented <strong>in</strong> C++ <strong>in</strong> the Maude eng<strong>in</strong>e. References 1. Aalst, W.M.P.v.d.: Interval timed coloured Petri nets and their analysis. In: Application and Theory of Petri Nets 1993. LNCS, vol. 691, pp. 453–472. Spr<strong>in</strong>ger (1993) 2. AlTurki, M., Meseguer, J.: <strong>Real</strong>-time rewrit<strong>in</strong>g semantics of Orc. In: Proc. PPDP’07. ACM (2007) 3. Alur, R., Dill, D.L.: A theory of timed automata. Theoretical Computer Science 126(2), 183–235 (1994) 4. Alur, R., Henz<strong>in</strong>ger, T.: Logics and models of real time: A survey. In: <strong>Real</strong> <strong>Time</strong>: Theory <strong>in</strong> Practice. LNCS, vol. 600. Spr<strong>in</strong>ger (1992)
<strong><strong>Time</strong>d</strong> <strong>CTL</strong> <strong>Model</strong> <strong>Check<strong>in</strong>g</strong> <strong>in</strong> <strong>Real</strong>-<strong>Time</strong> Maude 39 5. Alur, R., Courcoubetis, C., Dill, D.: <strong>Model</strong>-check<strong>in</strong>g <strong>in</strong> dense real-time. Inf. Comput. 104, 2–34 (May 1993) 6. Bae, K., Ölveczky, P.C., Al-Nayeem, A., Meseguer, J.: Synchronous AADL and its formal analysis <strong>in</strong> <strong>Real</strong>-<strong>Time</strong> Maude. In: ICFEM’11. LNCS, vol. 6991. Spr<strong>in</strong>ger (2011) 7. Bae, K., Ölveczky, P.C., Feng, T.H., Lee, E.A., Tripakis, S.: Verify<strong>in</strong>g hierarchical Ptolemy II discrete-event models us<strong>in</strong>g <strong>Real</strong>-<strong>Time</strong> Maude. Science of Computer Programm<strong>in</strong>g (2011), to appear, doi:10.1016/j.scico.2010.10.002 8. Baier, C., Katoen, J.P.: Pr<strong>in</strong>ciples of <strong>Model</strong> <strong>Check<strong>in</strong>g</strong>. MIT Press (2008) 9. Behrmann, G., David, A., Larsen, K.G.: A tutorial on uppaal. In: SFM-RT 2004. LNCS, vol. 3185. Spr<strong>in</strong>ger (2004) 10. Boronat, A., Ölveczky, P.C.: Formal real-time model transformations <strong>in</strong> MO- MENT2. In: FASE’10. LNCS, vol. 6013. Spr<strong>in</strong>ger (2010) 11. Boucheneb, H., Gardey, G., Roux, O.H.: T<strong>CTL</strong> <strong>Model</strong> <strong>Check<strong>in</strong>g</strong> of <strong>Time</strong> Petri Nets. J Logic Computation 19(6), 1509–1540 (2009) 12. Bouyer, P.: <strong>Model</strong>-check<strong>in</strong>g timed temporal logics. ENTCS 231, 323–341 (2009) 13. Clarke, E., Grumberg, O., Peled, D.A.: <strong>Model</strong> <strong>Check<strong>in</strong>g</strong>. MIT Press (1999) 14. Clarke, E.M., Grumberg, O., McMillan, K.L., Zhao, X.: Efficient generation of counterexamples and witnesses <strong>in</strong> symbolic model check<strong>in</strong>g. In: DAC ’95 (1995) 15. Clavel, M., Durán, F., Eker, S., L<strong>in</strong>coln, P., Martí-Oliet, N., Meseguer, J., Talcott, C.: All About Maude, LNCS, vol. 4350. Spr<strong>in</strong>ger (2007) 16. Eker, J., Janneck, J.W., Lee, E.A., Liu, J., Liu, X., Ludvig, J., Neuendorffer, S., Sachs, S., Xiong, Y.: Tam<strong>in</strong>g heterogeneity—the Ptolemy approach. Proceed<strong>in</strong>gs of the IEEE 91(2), 127–144 (2003) 17. Gardey, G., Lime, D., Magn<strong>in</strong>, M., Roux, O.H.: Roméo: A tool for analyz<strong>in</strong>g time Petri nets. In: CAV’05. LNCS, vol. 3576. Spr<strong>in</strong>ger, Ed<strong>in</strong>burgh, Scotland, UK (2005) 18. Katelman, M., Meseguer, J., Hou, J.: Redesign of the LMST wireless sensor protocol through formal model<strong>in</strong>g and statistical model check<strong>in</strong>g. In: Proc. FMOODS’08. LNCS, vol. 5051. Spr<strong>in</strong>ger (2008) 19. Larouss<strong>in</strong>ie, F., Markey, N., Schnoebelen, P.: Efficient timed model check<strong>in</strong>g for discrete-time systems. Theor. Comput. Sci. 353, 249–271 (2006) 20. Lepri, D., Ölveczky, P.C., Ábrahám, E.: <strong>Model</strong> check<strong>in</strong>g classes of metric LTL properties of object-oriented <strong>Real</strong>-<strong>Time</strong> Maude specifications. In: Proc. RTRTS’10. EPTCS, vol. 36, pp. 117–136 (2010) 21. Lien, E., Ölveczky, P.C.: Formal model<strong>in</strong>g and analysis of an IETF multicast protocol. In: Proc. SEFM’09. IEEE Computer Society (2009) 22. Markey, N., Schnoebelen, P.: TSMV: A Symbolic <strong>Model</strong> Checker for Quantitative Analysis of Systems. In: QEST. IEEE Computer Society (2004) 23. Morasca, S., Pezzè, M., Trubian, M.: <strong><strong>Time</strong>d</strong> high-level nets. The Journal of <strong>Real</strong>- <strong>Time</strong> Systems 3, 165–189 (1991) 24. Ölveczky, P.C.: Towards formal model<strong>in</strong>g and analysis of networks of embedded medical devices <strong>in</strong> <strong>Real</strong>-<strong>Time</strong> Maude. In: Proc. SNPD’08. IEEE (2008) 25. Ölveczky, P.C.: Semantics, simulation, and formal analysis of model<strong>in</strong>g languages for embedded systems <strong>in</strong> <strong>Real</strong>-<strong>Time</strong> Maude. In: Formal <strong>Model</strong><strong>in</strong>g: Actors, Open Systems, Biological Systems. LNCS, vol. 7000. Spr<strong>in</strong>ger (2011) 26. Ölveczky, P.C., Boronat, A., Meseguer, J.: Formal semantics and analysis of behavioral AADL models <strong>in</strong> <strong>Real</strong>-<strong>Time</strong> Maude. In: Proc. FMOODS/FORTE’10. LNCS, vol. 6117. Spr<strong>in</strong>ger (2010) 27. Ölveczky, P.C., Caccamo, M.: Formal simulation and analysis of the CASH schedul<strong>in</strong>g algorithm <strong>in</strong> <strong>Real</strong>-<strong>Time</strong> Maude. In: Proc. FASE’06. LNCS, vol. 3922. Spr<strong>in</strong>ger (2006)