Reactive Synthesis - Hands-on Exercise

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1 Reactive Synthesis - Hands-on Exercise Lectures: Moshe Vardi Hands-on exercise: Rüdiger Ehlers ExCAPE Expeditions in Computer Augmented Program Engineering 13 th June 2013 Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

2 Overview 1 Available Tools for LTL Synthesis 2 An overview of Acacia+ 3 Traffic Light Example 4 Rotation Sorter Exercise Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

3 Some tools for Linear-time Temporal Logic Synthesis Full LTL Lily (Jobstmann and Bloem, 2006) Unbeast (Ehlers, 2011) Acacia+ (Bohy et al., 2012) Subset of LTL Marduk/Ratsy (Bloem et al., 2010) JTLV synthesizer (Pnueli et al., 2010) Bassist (Ehlers, 2012) More tools: Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

4 Acacia+ (Bohy et al., 2012) Features Support for full LTL Optimized algorithms for specifications of the form φ 1 φ 2... φ n Can also optimize the solution towards mean-payoff objectives Techniques Is based on bounded synthesis (Schewe and Finkbeiner, 2007; Filiot et al., 2009), which in turn builds on Safraless synthesis (Kupferman and Vardi, 2005) Written in Python and C Interfaces with external LTL-to-automata translators Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

5 Example An intersection Interface AP I = {t n, t e, t w, t s } AP O = {g n, g e, g w, g s } Specification G(g s ( g e g w )) G(t s F g s )... Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

6 Extending the Example Improving the quality of service Idea: green light may only be given if car is detected. New conjuncts: G(g n t n ) G(g s t s ) G(g e t e ) G(g w t w ) Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

7 Extending the Example Improving the quality of service Idea: green light may only be given if car is detected. New conjuncts: G(g n t n ) G(g s t s ) G(g e t e ) G(g w t w ) The setting is unrealizable now! Reason: Trigger signal might be released before green light is given. So we cannot avoid a conflict of: G(t s F g s ) G(t w F g w ) G(g s ( g w g e )) G(g w ( g n g s )) G(g s t s ) G(g w t w ) Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

8 Extending the Example Improving the quality of service Idea: green light may only be given if car is detected. New conjuncts: G(g n t n ) G(g s t s ) G(g e t e ) G(g w t w ) The setting is unrealizable now! Reason: Trigger signal might be released before green light is given. So we cannot avoid a conflict of: G(t s F g s ) G(t w F g w ) G(g s ( g w g e )) G(g w ( g n g s )) G(g s t s ) G(g w t w ) Fixing unrealizability: adding assumptions (G((t s g s ) X t s )... G((t w g w ) X t w )) ψ Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

9 Rotation Sorter x1, y1 b1, p1 p2 x0, y0 b0, p0 Input/Output per direction Inputs x and y encode packet destinations Output p pushes packets off the rotating table Output b triggers the in-belt Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

10 Timing Example (transport packet by 240 ) x y p p p b Semantics Meaning x y No packet 0 0 Transport by Transport by Transport by (Almost) a possible part of the specification (x0 y0) (b0 X p1 XX p2 XXX p0) Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

11 Exercise Your turn! Link Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

12 More on the practical side of synthesis Suggestion Try out a synthesizer for generalized reactivity(1) specifications, such as, e.g., Marduk/Ratsy a, Gr1c b, or Slugs c. a b c Some light reading material R.E.: Experimental Aspects of Synthesis, International Workshop on Interactions, Games and Protocols (iwigp) 2011 Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

13 References I Roderick Bloem, Alessandro Cimatti, Karin Greimel, Georg Hofferek, Robert Könighofer, Marco Roveri, Viktor Schuppan, and Richard Seeber. Ratsy - a new requirements analysis tool with synthesis. In Touili et al. (2010), pages ISBN Aaron Bohy, Véronique Bruyère, Emmanuel Filiot, Naiyong Jin, and Jean-François Raskin. Acacia+, a tool for LTL synthesis. In Madhusudan and Seshia (2012), pages ISBN Rüdiger Ehlers. Unbeast: Symbolic bounded synthesis. In Parosh Aziz Abdulla and K. Rustan M. Leino, editors, TACAS, volume 6605 of Lecture Notes in Computer Science, pages Springer, ISBN Rüdiger Ehlers. ACTL LTL synthesis. In Madhusudan and Seshia (2012), pages ISBN Emmanuel Filiot, Naiyong Jin, and Jean-François Raskin. An antichain algorithm for LTL realizability. In Ahmed Bouajjani and Oded Maler, editors, CAV, volume 5643 of Lecture Notes in Computer Science, pages Springer, ISBN Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

14 References II Barbara Jobstmann and Roderick Bloem. Optimizations for LTL synthesis. In FMCAD, pages IEEE Computer Society, ISBN Orna Kupferman and Moshe Y. Vardi. Safraless decision procedures. In FOCS, pages IEEE Computer Society, ISBN P. Madhusudan and Sanjit A. Seshia, editors. Computer Aided Verification - 24th International Conference, CAV 2012, Berkeley, CA, USA, July 7-13, 2012 Proceedings, volume 7358 of Lecture Notes in Computer Science, Springer. ISBN Amir Pnueli, Yaniv Sa ar, and Lenore D. Zuck. Jtlv: A framework for developing verification algorithms. In Touili et al. (2010), pages ISBN Sven Schewe and Bernd Finkbeiner. Bounded synthesis. In Kedar S. Namjoshi, Tomohiro Yoneda, Teruo Higashino, and Yoshio Okamura, editors, ATVA, volume 4762 of Lecture Notes in Computer Science, pages Springer, ISBN Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

15 References III Tayssir Touili, Byron Cook, and Paul Jackson, editors. Computer Aided Verification, 22nd International Conference, CAV 2010, Edinburgh, UK, July 15-19, Proceedings, volume 6174 of Lecture Notes in Computer Science, Springer. ISBN Exercise: Rüdiger Ehlers (UCB/Cornell) Reactive Synthesis Berkeley, 13 th June / 10

Program Synthesis is a Game

Program Synthesis is a Game Barbara Jobstmann CNRS/Verimag, Grenoble, France Outline Synthesis using automata- based game theory. MoBvaBon, comparison with MC and LTL. Basics Terminology Reachability/Safety