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enumerative (or concrete) reactive synthesis tool for the GR(1) fragment of LTL

Project Description

gr1py is an enumerative (or concrete) reactive synthesis tool for the GR(1) fragment of LTL. It is pure Python.


Releases are available from the Python Package Index at To get it from there and check the version, try

pip install gr1py
gr1py -V

pip should get dependencies for you if you do not have them. They are

If it is available, NetworkX ( will be used. However, it is not required. A simple built-in class for directed graphs will be used if NetworkX is not found.

If you want to hack on gr1py, clone the repository from

Current CI server report:


Besides the Python package, a script named gr1py is installed that provides access to several routines from the command-line. Consider the file named examples/arbiter3.spc that is included in the source release. To check that the specification defined by it can be realized, try

gr1py -r examples/arbiter3.spc

To synthesize a winning strategy and dump it in the Graphviz DOT format, try

gr1py -t dot examples/arbiter3.spc >
dot -Tsvg -O

where the second command uses the program dot (part of Graphviz) to create an SVG file, likely named; e.g., the file can be displayed using a Web browser or Inkscape.

A summary of command-line usage can be obtained by grpy -h.

Input formats

The default input format is that of gr1c (

Output formats

These are selected from the command-line using the -t switch. Each corresponds to a function in gr1py.output.

Feedback and contributing

Bug reports, feature requests, and comments can be submitted via the project issue tracker or via email to the authors.

Code contributions are welcome. To avoid redundant effort, please check for an existing issue or other indication of prior or intended work before starting. When ready for review, send a pull request.


This is free software released under the terms of the BSD 3-Clause License. There is no warranty; not even for merchantability or fitness for a particular purpose. Consult LICENSE for copying conditions.

Release History

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