The ProB Animator and Model Checker

(Redirected from Main Page)

ProB is an animator, constraint solver and model checker for the B-Method. The constraint-solving capabilities of ProB can be used for animation, model finding, constraint-based symbolic checking and test-case generation.

The B language is rooted in predicate logic, arithmetic and set theory and provides support for data structures such as (higher-order) relations, functions and sequences. In addition to the B language, ProB also supports Event-B, CSP-M, TLA+, and Z. ProB can be installed within Rodin. ProB can also be used as a Jupyter kernel to generate interactive notebooks.

ProB is being used within Alstom, ClearSy, Siemens, Thales and several other companies for data validation of complicated properties for safety critical systems. It was used, e.g., for Paris Line1, Sao Paulo line 4, Barcelona line 9 and many more. ProB is certified T2 SIL4 according to the Cenelec EN 50128 standard for use at Thales. In this video from the Deutsche Bahn you can see ProB animating a formal B model of the ETCS hybrid-level 3 principles in real-time, controlling two trains. Michael Leuschel and his group have won the first edition of the AlainColmerauer Prize for ProB. For commercial support contact Michael Leuschel.

Versions of ProB

Several versions of ProB are available. They all make use of the same Prolog core (see below).


The core of ProB is implemented in SICStus Prolog (but can be run without a SICStus Prolog license). The ProB constraint solver is implemented using co-routining and the CLP(FD) finite domain library of SICStus. An alternate constraint solver based on Kodkod (and thus SAT) is also available within ProB, as is an integration with the SMT solver Z3. An alternate model checking engine (using TLC) well-suited for lower level B specifications is available as is an integration with LTSmin as model checking backend. The ProB Licence can be found here.


2024-02-20 ProB 1.13.0 is available. Better Rodin theory support. Template strings. READ_JSON and other new external functions. VisB support for groups and "use" element. MCTS game play.

2023-08-10 ProB 1.12.2 is available. VisB improvements.

2023-04-04 ProB 1.12.0 is available. Call stack infos, performance improvements in parser and solver, new LTL operators, VisB improvements, reals/floats for Rodin theories.

2022-11-10 Michael Leuschel and his group win first edition of Colmerauer Prize for ProB

2021-12-29 ProB 1.11.1 is available. Identifiers between backquotes, flexible JSON trace replay, DPLLT solving, improvements to Z3 backend.

2021-10-06 ProB 1.11.0 is available. Improved support for infinite sets, operation caching, faster LTL checking for safety formulas, more compact .prob files, VisB HTML export, constructive Z3 translation.

2021-01-26 ProB2-UI 1.1.0 is available, contains VisB.

2020-12-15 ProB 1.10.0. Highlights: well-definedness prover, REAL datatype, -lint comand for VSCode and Atom, improved unsat core.

2020-02-19 ProB 1.9.3. Highlights: performance improvements, new external functions, performance monitoring.

2019-07-12 ProB 1.9.0. Highlights: Unicode support, regular expression library, memoization. New ProB2 UI.

2018-10-01 ProB 1.8.2. Highlights: Jupyter kernel, first support for Alloy models.

2017-07-11 ProB 1.7.0 Highlights: improved Latex document generation, improved XML/CSV support.

2016-10-20 ProB 1.6.1 Highlights: LET and IF-THEN-ELSE for expressions and predicates.

2016-04-22 ProB 1.6.0 highlights: directed model checking, Z3 as backend.

2014-08-18 ProB 1.4.0 is available. Highlights: CLP(FD)-based constraint solver enabled by default, integration of the TLC model checker.

2012-03-30 ProB Logic Calculator available.

More in Release History


ProB covers a large part of B, and we are striving towards full coverage of Atelier B constructs. ProB supports B features such as non-deterministic operations, arbitrary quantification, sets, sequences, functions, lambda abstractions, set comprehensions, records, and many more. ProB does support multiple machines, refinements, and implementations. ProB can also be used for automated refinement checking and LTL model checking. It also supports CSP-M process descriptions, to be used on their own or to guide B machines for specification and property validation. The state space of the specifications can be graphically visualized. ProB supports Z specifications (ProB in this context is sometimes called ProZ) as well as TLA+ specifications. ProB can be used within Rodin and Atelier-B as a disprover and prover.


Citing ProB

The initial conference publication was:

  • Michael Leuschel & Michael Butler (2003): ProB: A Model Checker for B. In Keijiro Araki, Stefania Gnesi & Dino Mandrioli, editors: FME 2003: Formal Methods, LNCS 2805, Springer-Verlag, pp. 855–874, doi:10.1007/978-3-540-45236-2 46.

A later journal article describes ProB in more detail:

For convenience we also provide Bibtex entries for the above references.