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Outline. Preliminary BACH Path-Oriented Reachability Checker Bounded Reachability Checker Case Study Conclusion. Preliminary BACH Path-Oriented Reachability Checker Bounded Reachability Checker Case Study Conclusion. Preliminary. Hybrid System:
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Outline • Preliminary • BACH • Path-Oriented Reachability Checker • Bounded Reachability Checker • Case Study • Conclusion FMCAD08
Preliminary • BACH • Path-Oriented Reachability Checker • Bounded Reachability Checker • Case Study • Conclusion FMCAD08
Preliminary • Hybrid System: Systems contain both discrete and continuous components • Practical Examples: • Embedded System Controller • VLSI circuits • Linear Hybrid Automata: • Widely studied formal models for hybrid systems FMCAD08
State of The Art General Reachability BMC Reachability Technique SAT+LP Tool HySAT MathSAT Limitation Encoding->Huge Formula->Memory…? • Technique • Polyhedral-Computation • Tool • HyTech • PHAVer • Limitation • Exponential Complexity FMCAD08
Motivation • Path-oriented Reachability Checking By LP • Encoding: linear complexity • Solving: polynomial complexity • Depth First Search Enumeration • Online Checking: Only one path in the memory FMCAD08
Preliminary • BACH • Path-Oriented Reachability Checker • Bounded Reachability Checker • Case Study • Conclusion FMCAD08
BACH • LHA Reachability • Java Based Tool • Linear Programming Solver : OR-Objects. http://OpsResearch.com/OR-Objects/index.html • Available online: http://seg.nju.edu.cn/BACH/BACH.html FMCAD08
BACH Structure FMCAD08
BACH Functionality • Graphical LHA Editor • Reachability Checker • Path-oriented Reachability Checker • Bounded Reachability Checker FMCAD08
Path-Oriented Reachability Check Water-Level Monitor Path: v0ˆv1ˆv2ˆv3ˆv4ˆv1ˆv5 • time sequence representation: (v0, t0)ˆ(v1, t1)ˆ(v2, t2)ˆ(v3, t3) ˆ(v4, t4)ˆ(v1, t5)ˆ(v5, t6) -> ti ≥ 0, t0 = 0 • location invariant encoding: y ≤ 10 in location v1 -> yv1in ≤ 10, yv1out ≤ 10, yv1in +t1 = yv1out , • transition guard encoding: y = 10 in transition e1-> yv1out = 10 • reset action encoding y := 1 in transition e0-> yv1in = 1 FMCAD08
Bounded Reachability Check Water-Level Monitor Bound: 6 Target: v5 v0ˆv1 v0ˆv1ˆv2 v0ˆv1ˆv2ˆv3 v0ˆv1ˆv2ˆv3ˆv4 v0ˆv1ˆv2ˆv3ˆv4ˆv1 v0ˆv1ˆv2ˆv3ˆv4ˆv1ˆv2 v0ˆv1ˆv2ˆv3ˆv4ˆv1ˆv5 v0ˆv1ˆv5 Backtracking FMCAD08 • 2014/9/12 • 12
Preliminary • BACH • Path-Oriented Reachability Checker • Bounded Reachability Checker • Case Study • Conclusion FMCAD08
Case Study Water Level Monitor Temperature Controller FMCAD08
Path-Oriented Reachability Check FMCAD08
Bounded Reachability Check • Scalability • Performance FMCAD08
Preliminary • BACH • Path-Oriented Reachability Checker • Bounded Reachability Checker • Case Study • Conclusion FMCAD08
Conclusion • Convenient Tool • Graphical LHA Editor • Reachability Checker • Path-oriented Reachability Checker • Bounded Reachability Checker • Linear Programming Based Verification • Depth-First-Search Based Traverse • Good Scalability and Performance FMCAD08
Thanks Q&A FMCAD08