Discrete time model checking of Timed- Arc Petri nets

Project DetailsThe tool TAPAAL is created for verification of real-time systems — that is we canexpress timing constraints with real values. However often we don’t need the fullpower of real values to do model checking. A folklore result says that given the rightconstraints we can use integer values instead of real values when preforming verification.This is often called discrete time.This project will explore one of both of the following directions. Implement a integertime model checking engine for TAPAAL and/or prove the correctness of this folkloreresult.A successful project will (among other) include:• A survey of recent development in the area of automated verification of real-timesystems,• proof of the correctness of discrete time,• experimental results comparing the discrete time approtch to TAPAAL currentverification engine.• a code contribution that can be used in TAPAAL.The project can be adjusted to more theoretical (theory and algorithms) or practicallevel (algorithms and tools) according your wishes.In case that interesting results are achieved you are expected to contribute in transformingthese results into a conference/workshop paper suitable for publication.For more information or questions contact Kenneth Yrke Joergensen and agree on an informal meeting.2

Evaluation of real-time model checkingtoolsIntroduction to formal verificationWhen creating a computer system we want to avoid creating bugs. The predominantmethod to avoid bugs in industry is by testing the software. Model checking is a formalmethod that builds on a mathematical foundation for proving the absence or presencesof bugs in a system. Model checking is performed by creating a model of the system ina formal description language. We can input this model into a model checking tool toverify properties about the system. Properties can be questions like: will this systemreach a deadlock, can we always avoid this particular bad situation and, if we allowtime in our model, does event B happen exactly 10 time units before event A.You can read more about model checking at: http://en.wikipedia.org/wiki/Model_checkingTAPAALTAPAAL is a verification tool for a model called Timed-Arc Petri nets (TAPN).TAPN is a interesting model because it can capture many features of real-time systemswhile still preserving intuitive understanding and simple notation. TAPAAL is develophere at Aalborg University in 2008/2009.The tool TAPAAL features a:• graphical tool for modelling of TAPN,• a graphical simulator of TAPN and• a automatic verifier for TAPNTAPAAL is today actively develop by a development team of 5 students and employeesat Aalborg University.You can read more about TAPAAL at www.tapaal.net1

Project DetailsFigure 1: Screenshot of the TAPAAL guiThis project will compare a number of different real-time model checking tools to comparedifferent parameters such as: tool usability, tool performance and modeling power,by modelling one or more algorithms (eg. mutual exclusions or networks algorithms)The result would be a survey describing the strengths and weaknesses of the differenttools, and possible propose and implement ideas for the development of TAPAAL.A successful project will (among other) include:• A survey of recent development in the area of automated verification of real-timesystems,• modelling and verification of a algorithm in several state-of-the-art model checkingtools,• a comparison of model checking tools summarising strengths and weaknesses ofthe different tools,• experimental results comparing the different model checkers and• a number of ideas for changes/features to TAPAAL and possibly the implementationof some of these into TAPAAL.The project can be adjusted to more theoretical (theory and algorithms) or practicallevel (algorithms and tools) according your wishes.In case that interesting results are achieved you are expected to contribute in transformingthese results into a conference/workshop paper suitable for publication.2

For more information or questions contact Kenneth Yrke Joergensen and agree on an informal meeting.3

Verifying stateful timed CSPusing UPPAALIntroduction to formal verificationWhen creating a computer system we want to avoid creating bugs. The predominantmethod to avoid bugs in industry is by testing the software. Model checking is a formalmethod that builds on a mathematical foundation for proving the absence or presencesof bugs in a system. Model checking is performed by creating a model of the system ina formal description language. We can input this model into a model checking tool toverify properties about the system. Properties can be questions like: will this systemreach a deadlock, can we always avoid this particular bad situation and, if we allowtime in our model, does event B happen exactly 10 time units before event A.You can read more about model checking at: http://en.wikipedia.org/wiki/Model_checkingStateful Timed CSPIn 2009 Jun Sun et.al. introduced the notion of Stateful Timed CSP as a model for ahigh-level description computer systems that include timing constraints. The languageintroduces several high level therms such as deadline, time out, and timed interrupt,to eliminate human errors that can made when using low level description languages.The verification of Stateful Timed CSP has been implemented into the authors ownmodel checking tool PAT.Figure 1: Example of the Stateful Timed CSP languageProject DetailsAlthough PAT is a fast developing real-time model checker, the model checker UPPAAL(developed partly in Aalborg) is still considered one of the best and fastest modelcheckers. The project would consist of adding support of ”Stateful Timed CSP” in1

UPPAAL by creating a tool to translate Stateful Timed CSP into networks of timedautomata that can be verified by UPPAAL. The goal would be to directly compare thetwo model checking tools.A successful project will (among other) include:• An algorithms translating from Stateful Timed CSP to networks of timed automata,• a prototype tool for translating (a subset of) Stateful Timed CSP into TimedAutomata,• proof of the correctness of the translation, and• experimental results comparing verification time between PAT and UPPAAL.The project can be adjusted to more theoretical (theory and algorithms) or practicallevel (algorithms and tools) according your wishes.In case that interesting results are achieved you are expected to contribute in transformingthese results into a conference/workshop paper suitable for publication.For more information or questions contact Kenneth Yrke Joergensen and agree on an informal meeting.2

New TAPAAL verification engineIntroduction to formal verificationWhen creating a computer system we want to avoid creating bugs. The predominantmethod to avoid bugs in industry is by testing the software. Model checking is a formalmethod that builds on a mathematical foundation for proving the absence or presencesof bugs in a system. Model checking is performed by creating a model of the system ina formal description language. We can input this model into a model checking tool toverify properties about the system. Properties can be questions like: will this systemreach a deadlock, can we always avoid this particular bad situation and, if we allowtime in our model, does event B happen exactly 10 time units before event A.You can read more about model checking at: http://en.wikipedia.org/wiki/Model_checkingTAPAALTAPAAL is a verification tool for a model called Timed-Arc Petri nets (TAPN).TAPN is a interesting model because it can capture many features of real-time systemswhile still preserving intuitive understanding and simple notation. TAPAAL is develophere at Aalborg University in 2008/2009.The tool TAPAAL features a:• graphical tool for modelling of TAPN,• a graphical simulator of TAPN and• a automatic verifier for TAPNTAPAAL is today actively develop by a development team of 5 students and employeesat Aalborg University.You can read more about TAPAAL at www.tapaal.netProject DetailsThe tool TAPAALs verification engine works by translating problems into somethinga verification engine can understand. At the moment the engine used in TAPAAL iscalled UPPAAL. However there exists many other tools that might be suitable as theverification engine for TAPAAL. TAPAAL architecture makes it easy to change theverification engine to try out other model checkers. The task world be to choose a tooland try it out as a new verification engine for TAPAAL.A successful project will (among other) include:1

• A survey of recent development in the area of automated verification of real-timesystems,• A translation from TAPN to the chosen new engine and possibly proof of correctnessof the translation,• experimental results comparing the new and old verification engines for TAPAALand• a code contribution that can be used directly in TAPAAL.The project can be adjusted to more theoretical (theory and algorithms) or practicallevel (algorithms and tools) according your wishes.In case that interesting results are achieved you are expected to contribute in transformingthese results into a conference/workshop paper suitable for publication.For more information or questions contact Kenneth Yrke Joergensen and agree on an informal meeting.2