1 / 14

ProB and XTL : Model checkers for B and DSSLs

ProB and XTL : Model checkers for B and DSSLs. Michael Leuschel University of Southampton. ProB: Why?. Animate a B-specification No need for user to guess parameters Verify a B-Specification Temporal & State-Based model checking Test-case generation & synchronise with implementation

telma
Download Presentation

ProB and XTL : Model checkers for B and DSSLs

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ProB and XTL :Model checkers for B and DSSLs Michael Leuschel University of Southampton

  2. ProB: Why? • Animate a B-specification • No need for user to guess parameters • Verify a B-Specification • Temporal & State-Based model checking • Test-case generation & synchronise with implementation • Benefits • Gain confidence in specifications • Detect bugs before attempting formal proofs • Check final implementation againts spec • Learn how B works

  3. ProB: Internals XML Encoding Parser & Specialiser B Machine Tatibouet’s Parser Prolog Encoding Java B-Interpreter CLP B-Kernel b_execute_statement b_evaluate_expression … subset_of partial_function add … Everything except Tatibouet’s parser: in SICStus Prolog

  4. Temporal vs State-Based MC • Temporal • Start from initial state • Find sequence of operations that lead to error • Examples: Spin, SMV, … • Model/State Based • No concept of initial state • Find a valid state (satisfies invariant) such that applying a single operation leads to an error • Example: Alloy

  5. ProB: A Demo • Animation • Temporal Model Checking • State-Based Model Checking • Visualization • Linking with Java implementation

  6. And now for something different: XTL • XTL • Written in XSB-Prolog • Exhaustive, finite state model checker for • CTL specifications • Systems represented in XSB-Prolog (e.g., interpreters!) • Ok, but why YAP (Yet Another Prolog) ?

  7. Prolog: The Base XSB Prolog SICStus Prolog Ciao Prolog Other players: Mercury (.Net), SWI-Prolog, Yap, IF-Prolog

  8. Tabling: what’s all the fuss? :- table p/0. q :- p. p :- p. r :- not q. :- table path/3. path(X,X,[]). path(X,Y,[X|T]) :- arc(X,Z), path(Z,Y,T). arc(a,b). arc(b,a). • What it does for you: • Loop checking • Answer Propagation • Program at a higher-level& Speed! • XSB can be used as deductive database • Useful for parsing • Useful for verification :- table model_check/1, model_check/2. model_check(S) :- prop(S,unsafe). model_check(S) :- trans(_,S,NS), model_check(NS). model_check(S,[]) :- prop(S,unsafe). model_check(S,[A|T]) :- trans(A,S,NS), model_check(NS,T).

  9. Tabling II • Loop checking can be easily done in Prolog: e.g., assert/retract • But: • No answer propagation • Speed!(using CSM from Babylon) :- dynamic tabled/1. check_table(X) :- (tabled(X) -> (fail) ; assert(tabled(X))). model_check(S) :- prop(S,unsafe). model_check(S) :- trans(_,S,NS), check_table(NS),model_check(NS).

  10. Tabling vs Assert - Bench XSB: 2: 0.0000 s - 76 states 4: 0.0090 s - 340 states 8: 0.1190 s - 1956 states 16: 1.0810 s - 13124 states 24: 4.5800 s - 41700 states 32: 10.0690 s - 95876 states SICSTUS - assert 2: 0.010 s - 76 states 4: 0.260 s - 340 states 8: 11.250 s - 1956 states 16: 772.500 s - 13124 states

  11. Summary of our Tools ECCE Online specialiser For pure Prolog Can do infinite state MC ProB model checker & animator for B XTL finite state model checker for any system encoded in XSB Prolog LOGEN Fast offline specialiser & compiler generator for Prolog StAC XSB Prolog SICStus Prolog Ciao Prolog

  12. XTL • Model checker for finite state systems • Written in XSB-Prolog • Pure & simple: • Can be analysed and specialised by other systems • Generic: • Can handle any system described in (XSB)-Prolog • Ex: Writing an interpreter for StAC in XSB is much easier than writing a compiler to Promela! (interpreter) • Efficient despite flexibility!

  13. *** = out of memory One Benchmark: CSM (from Babylon) XTL Spin (wo compilation time, wo time to find search depth) FDR XSB 2.5 G4 667Mhz 500Mb XSB 2.4 Livelock Testing Refinement

  14. Future Work • Full scale application of XTL to StAC • Integrate Logen into ProB &XTL • Extend ProB to handle more of B, check refinement • Apply XTL to Proforma, <insert your favourite lge here>,… • Apply XTL to ProB-interpeter • Apply ECCE for infinite state MC

More Related