Chloe - Characterizing languages of open systems

Chloe is a tool to create the labeled transitions systems CSD and BSD to decide bounded responsiveness with Delain.

See the science section for additional information.

Chloe Science

Chloe is based on theory introduced in several scientific publications.

Deciding b-Conformance and b-Responsiveness for Open Systems

The labeled transition systems (LTSs) CSD and BSD created with Chloe are part of a theory to decide if compositions of open systems are correct. The correctness criterion is bounded responsiveness. The tool Delain is used to decide conformance/responsiveness using the LTS constructed by Chloe. The overall theory is introduced in the following publications:

Optimizing the Construction of the LTS CSD/BSD

Chloe's main function is to generate the LTSs CSD_b(N) and BSD_b(N) from given open net N and a bound b. The reachability graph of inner(N) is calculated by LoLA and used to compute the LTSs CSD_b(N) and BSD_b(N). DOT files are generated as output.

Chloe 3 is a complete rewrite of Chloe with a new algorithm and many additional optimizations. The new algorithm and the optimizations are described here:

Download Chloe

Version history

Chloe has been developed for quite some time now. See the ChangeLog for details or try out the older versions.


Chloe is open source software, licensed under the AGPL3+.

Install Chloe


Installing and running Chloe requires a bunch of other tools:

Compiling requires:

  • GCC - The GCC compiler

Testing requires:

  • LCOV - LCOV is a graphical front-end for GCC's coverage testing tool gcov. It collects gcov data for multiple source files and creates HTML pages containing the source code annotated with coverage information.
  • Valgrind - Valgrind is an instrumentation framework for building dynamic analysis tools. There are Valgrind tools that can automatically detect many memory management and threading bugs, and profile your programs in detail.
  • Autotools test suite - Part of the GNU Auto-Tools for automated Tests

Contributing requires:

  • GNU Gengetopt - Gengetopt generates a C function that uses getopt_long function to parse the command line options, to validate them and fills a struct .
  • Bison - Gnu parser generator - Bison is a general-purpose parser generator that converts an annotated context-free grammar into a deterministic LR or generalized LR (GLR) parser employing LALR(1) parser tables.
  • flex: The Fast Lexical Analyzer - Flex is a tool for generating scanners. A scanner, sometimes called a tokenizer, is a program which recognizes lexical patterns in text. The flex program reads user-specified input files, or its standard input if no file names are given, for a description of a scanner to generate.

Quick install

Extract the tar ball into a folder of your choice, and follow the steps below.

  1. Configure
  2. Compile
  3. Test (optional, but recommended)
    make check
  4. Install
    sudo make install


Chloe's manual explains usage, features, and a brief scientifical background. If you are further interested learning more about the science behind Chloe, please consult Chloe's science section.


Chloe's documentation aims at the developer in you. If you are interested in implementation details this is the right place for you to look.


The current maintainer of Chloe is Johannes Dewender.


Johannes Dewender implemented the new algorithm and the optimizations.


Several people have committed time, code, and advice to the development of Chloe.

  • Johannes Dewender (216 commits)


Chloe's development team thanks:

  • Richard Müller for ideas, help and the theory
  • Niels Lohmann for creating Wendy and writing several relevant papers
  • Simon Heiden for creating the original Chloe