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This is a fork of Fast Downward extended with an implementation of the hCFF heuristic and online refinement of explicit conjunctions. This implementation has been used for experiments in the following literature:

It is also the code base of OLCFF and parts of Saarplan; both planners competed in the International Planning Competition 2018.

The hCFF heuristic and online-refinement search engines are implemented in src/search/conjunctions. The best-performing configurations of RHC, RHC-SC, and GBFS-SCL from the JAIR'22 paper have corresponding aliases (see driver/, so they can be run as follows:

./ --alias RHC task.pddl
./ --alias RHC-SC task.pddl
./ --alias GBFS-SCL task.pddl

The jair22-data.tar.xz file contains the raw data from the JAIR'22 experiments (in the Downward Lab JSON format).

The code also contains a copy of the h2 preprocessor (Alcazar and Torralba, ICAPS'15), which can be enabled by prepending the --transform-task=preprocess driver option.

Fast Downward

Fast Downward is a domain-independent planning system.

For documentation and contact information see

The following directories are not part of Fast Downward as covered by this license:

  • ./src/search/ext

For the rest, the following license applies:

Fast Downward is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later

Fast Downward is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program. If not, see <>.


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