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Fast Downward Releases
Fast Downward uses time-based version numbers of the form YY.MM. For example, Fast Downward 19.06 was originally released in June 2019. We intend to follow a 6-monthly release cycle, but this is not set in stone. Bugfix releases are numbered as 19.06.1, 19.06.2 and so on.
Fast Downward is research software, and we do not provide extensive support for past releases. In particular, we generally do not backport bug fixes. Bug fix releases are intended to be a rare exception to address critical problems that can be backported with reasonable effort, such as incompatibilities with new compiler versions. Bug fix releases are generally limited to the latest release series.
Releases since 2019
Fast Downward has been in development since 2003, but we only started using the current release model in 2019. From 2008 onwards, various versions of Fast Downward and related planners were released as part of the International Planning Competition series.
From 2003-2006, Fast Downward used no formal version control. From 2006-2010, the code was developed in a Subversion repository, from 2010-2020 in a Mercurial repository, and since July 2020 in a Git repository. The Git repository includes history dating back to 2006, but the migrations to Mercurial and to Git involved some pruning, in addition to differences caused by the different data models of these version control systems. If you need access to any of the historical code (pre-version-control era, Subversion era, or Mercurial era), feel free to contact us <firstname.lastname@example.org>.
The legacy Mercurial repository http://hg.fast-downward.org/ is still available, but will be taken offline at the time of release of Fast Downward 20.12 (not before December 1, 2020). Please note that this repository has been frozen in July 2020, and we do not recommend using it for purposes other than converting your own clones to Git.
Note that Mercurial repositories compatible with the legacy Mercurial repository can be converted to Git repositories that are compatible with our Git repository. If your repository branched off this Mercurial repository, we recommend using our conversion script.