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Differential Refinement Logic Sarah M. Loos and Andr Platzer Computer Science Department Carnegie Mellon University 1 Verified Cyber-Physical Systems [FM11] 2 Verified Cyber-Physical Systems x l x j p x k x i


  1. Contributions Differential Refinement Logic � Maintains a modular and hierarchical proof structure � Abstracts implementation-specific designs � Leverages iterative system design � Prove time-triggered model refines event-triggered � Encouraging evidence of reduced user interaction and computation time 67

  2. Appendix 68

  3. Comparing dRL and dL We have proved that the refinement relation can be embedded in dL. As a result, dL and dRL are equivalent in terms of expressibility and provability . However, we can analyze dRL on familiar (challenging) case studies. We can consider: • Number of proof steps • Computation time • Qualitative difficulty to complete proof • Proof structure 69

  4. Semantics of hybrid programs iff except for ρ ( x := θ ) = v = w the value of v w ρ ( x ρ ( x := θ ) = ) = { ( v, w ) : w = v except [[ x ]] w = [[ θ ]] v } ? ψ | Iff holds in state = ψ v v ρ (? ψ ) = ) = { ( v, v ) : v | = ψ } x 0 = θ If solves x 0 = θ y ( t ) v w x := y ( t ) ρ ( x 0 = θ ) = { ( ϕ (0) , ϕ ( t )) : ϕ ( s ) | = x 0 = θ for all 0 ≤ s ≤ t } [Platzer08] 70

  5. Semantics of hybrid programs α ; β v u w β α ρ ( α ; β ) = { ( v, w ) : ( v, u ) ∈ ρ ( α ) , ( ) , ( u, w ) ∈ ρ ( β ) } [Platzer08] 71

  6. Combining refinement and diamond modality 72

  7. Nondeterministic Assignment 73

  8. Nondeterministic Assignment ρ ( x := θ ) = v J θ K v v J x x 74

  9. Nondeterministic Assignment v d 1 ∗ x = : x i h ρ ( x := θ ) = v J θ K v v J v J v d 2 x := ∗ x x x x x := ∗ v d 3 hi x 75

  10. Nondeterministic Assignment v d 1 ∗ x = : x i h ρ ( x := θ ) = v J θ K v v J v J v d 2 x := ∗ x x x x x := ∗ v d 3 hi x 76

  11. Nondeterministic Repetition α ∗ … α α α v w 77

  12. Nondeterministic Repetition α ∗ … α α α v w β 78

  13. Nondeterministic Repetition α ∗ … α α α v w β ? β 79

  14. Nondeterministic Repetition α ∗ … α α α v w β ? β 80

  15. Nondeterministic Repetition α ∗ … α α α v w β β 81

  16. Nondeterministic Repetition α ∗ … α α α v w β ? β β 82

  17. Nondeterministic Repetition α ∗ … α α α v w β ? β β 83

  18. Nondeterministic Repetition α ∗ … α α α v w β β β 84

  19. Nondeterministic Repetition α ∗ … α α α v w β β β β ∗ 85

  20. Nondeterministic Repetition (KAT style) 86

  21. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v 87

  22. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v 88

  23. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v 89

  24. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v γ ? 90

  25. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v γ ? 91

  26. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v γ 92

  27. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v γ ? γ 93

  28. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v γ ? γ 94

  29. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v γ ? γ 95

  30. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v γ γ 96

  31. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v γ … γ γ 97

  32. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v γ … γ γ γ 98

  33. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v 99

  34. Nondeterministic Repetition (KAT style) … β α α w 1 w 2 w 3 w 4 v … γ γ γ γ 100

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