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* simplify nullability in ClassicLStarMealy and ClassicLStarMoore implementations
* do not call overridable methods in constructor of AbstractDTLearner
* add some additional null checks in OML implementations

overall these changes result in passing CF checks for all active leaners

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LearnLib is a free, open source (Apache License, v2.0) Java library for automata learning algorithms.


LearnLib is mainly developed at the Dortmund University of Technology, Germany. Its original purpose is to provide a framework for research on automata learning algorithms as well as for their application in practice.

The public version is a re-implemented version of the former closed-source version of LearnLib. While certain features have been stripped for improved modularity, development has since then extended the features offered. Currently, the following learning algorithms with respective target models are supported:

Algorithm (active) Target models Algorithm (passive) Models
DHC Mealy RPNI DFA Mealy
Discrimination Tree DFA Mealy Moore VPDA RPNI (EDSM) DFA
Kearns & Vazirani DFA Mealy RPNI (MDL) DFA
L* (incl. variants) DFA Mealy Moore
TTT DFA Mealy Moore VPDA

Additionally, LearnLib offers a variety of tools to ease the practical application of automata learning on real-world systems. This includes drivers and mappers for interfacing software systems with the LearnLib API as well as caches and parallelization for improving the overall performance of the learning setup. Also, more nuanced setups such as Black-Box-Checking (via LTSMin) or inferring partial machines are possible.

While we strive to deliver code at a high quality, please note that there exist parts of the library that still need thorough testing. Contributions -- whether it is in the form of new features, better documentation or tests -- are welcome.

Build Instructions

For simply using LearnLib you may use the Maven artifacts which are available in the Maven Central repository. It is also possible to download a bundled distribution artifact if you want to use LearnLib without Maven support. Note that LearnLib requires Java 8 or newer.

Building development versions

If you intend to use development versions of LearnLib, you can either use the deployed SNAPSHOT artifacts from the continuous integration server (see Using Development Versions), or build them yourself. Simply clone the development branch of the repository

git clone -b develop --single-branch

and run a single mvn clean install. This will build all the required maven artifacts and will install them in your local Maven repository so that you can reference them in other projects.

If you plan to use a development version of LearnLib in an environment where no Maven support is available, simply run mvn clean package -Pbundles. The respective JARs are then available under distribution/target/bundles.

Note: Development versions of LearnLib usually depend on development versions of AutomataLib. For building development versions of AutomataLib, see the corresponding documentation on the project's README.

Developing LearnLib

For developing the code base of LearnLib it is suggested to use one of the major Java IDEs which come with out-of-the-box Maven support.

  • For IntelliJ IDEA:

    1. Select File -> New -> Project from existing sources and select the folder containing the development checkout.
    2. Choose "Import Project from external model", select "Maven" and click Next.
    3. Configure the project to your liking but make sure to check "Import Maven projects automatically" and have "Generated sources folders" set to "Detect automatically".
    4. Click Next until the project is imported (no Maven profile needs to be selected).
    5. In order to have both development versions of AutomataLib and LearnLib available at once, continue to import AutomataLib as documented in the project's README, but choose File -> New -> Module from existing sources as the first step.
  • For Eclipse:

    1. Note: LearnLib uses annotation processing on several occasions throughout the build process. This is usually handled correctly by Maven, however, for Eclipse you need to install the m2e-apt-plugin and activate annotation processing afterwards (see the issue #32).
    2. Select File -> Import... and select "Existing Maven Projects".
    3. Select the folder containing the development checkout as the root directory and click Finish.
    4. In order to have both development versions of AutomataLib and LearnLib available at once, continue to import AutomataLib as documented in the project's README.


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